diff --git a/pkg/util/resource.go b/pkg/util/resource.go
index cab646d5c..c5bb5c4f6 100644
--- a/pkg/util/resource.go
+++ b/pkg/util/resource.go
@@ -20,7 +20,7 @@ type Resource struct {
 	ScalarResources map[corev1.ResourceName]int64
 }
 
-// EmptyResource creates a empty resource object and returns.
+// EmptyResource creates an empty resource object and returns.
 func EmptyResource() *Resource {
 	return &Resource{}
 }
@@ -58,6 +58,10 @@ func (r *Resource) Add(rl corev1.ResourceList) {
 
 // SubResource is used to subtract two resources, if r < rr, set r to zero.
 func (r *Resource) SubResource(rr *Resource) *Resource {
+	if r == nil || rr == nil {
+		return r
+	}
+
 	r.MilliCPU = MaxInt64(r.MilliCPU-rr.MilliCPU, 0)
 	r.Memory = MaxInt64(r.Memory-rr.Memory, 0)
 	r.EphemeralStorage = MaxInt64(r.EphemeralStorage-rr.EphemeralStorage, 0)
@@ -182,33 +186,6 @@ func (r *Resource) MaxDivided(rl corev1.ResourceList) int64 {
 	return res
 }
 
-// LessEqual returns whether all dimensions of resources in r are less than or equal with that of rr.
-func (r *Resource) LessEqual(rr *Resource) bool {
-	lessEqualFunc := func(l, r int64) bool {
-		return l <= r
-	}
-
-	if !lessEqualFunc(r.MilliCPU, rr.MilliCPU) {
-		return false
-	}
-	if !lessEqualFunc(r.Memory, rr.Memory) {
-		return false
-	}
-	if !lessEqualFunc(r.EphemeralStorage, rr.EphemeralStorage) {
-		return false
-	}
-	if !lessEqualFunc(r.AllowedPodNumber, rr.AllowedPodNumber) {
-		return false
-	}
-	for rrName, rrQuant := range rr.ScalarResources {
-		rQuant := r.ScalarResources[rrName]
-		if !lessEqualFunc(rQuant, rrQuant) {
-			return false
-		}
-	}
-	return true
-}
-
 // AddPodTemplateRequest add the effective request resource of a pod template to the origin resource.
 // If pod container limits are specified, but requests are not, default requests to limits.
 // The code logic is almost the same as kubernetes.
@@ -275,6 +252,10 @@ func (r *Resource) AddResourcePods(pods int64) {
 
 // Clone returns a copy of this resource.
 func (r *Resource) Clone() *Resource {
+	if r == nil {
+		return nil
+	}
+
 	res := &Resource{
 		MilliCPU:         r.MilliCPU,
 		Memory:           r.Memory,
diff --git a/pkg/util/resource_test.go b/pkg/util/resource_test.go
index dfb09178e..806af2153 100644
--- a/pkg/util/resource_test.go
+++ b/pkg/util/resource_test.go
@@ -21,12 +21,16 @@ func TestNewResource(t *testing.T) {
 				corev1.ResourceMemory:           *resource.NewQuantity(5, resource.BinarySI),
 				corev1.ResourcePods:             *resource.NewQuantity(5, resource.DecimalSI),
 				corev1.ResourceEphemeralStorage: *resource.NewQuantity(5, resource.BinarySI),
+				"test.karmada.io/foo":           *resource.NewQuantity(5, resource.BinarySI),
 			},
 			want: &Resource{
 				MilliCPU:         5,
 				Memory:           5,
 				EphemeralStorage: 5,
 				AllowedPodNumber: 5,
+				ScalarResources: map[corev1.ResourceName]int64{
+					"test.karmada.io/foo": 5,
+				},
 			},
 		},
 	}
@@ -39,3 +43,584 @@ func TestNewResource(t *testing.T) {
 		})
 	}
 }
+
+func TestResource_SubResource(t *testing.T) {
+	type args struct {
+		r  *Resource
+		rr *Resource
+	}
+	tests := []struct {
+		name string
+		args args
+		want *Resource
+	}{
+		{
+			name: "r is nil",
+			args: args{
+				r: nil,
+				rr: &Resource{
+					MilliCPU:         10,
+					Memory:           10,
+					EphemeralStorage: 10,
+					AllowedPodNumber: 10,
+					ScalarResources: map[corev1.ResourceName]int64{
+						"test.karmada.io/foo": 10,
+						"test.karmada.io/bar": 10,
+					},
+				},
+			},
+			want: nil,
+		},
+		{
+			name: "rr is nil",
+			args: args{
+				r: &Resource{
+					MilliCPU:         10,
+					Memory:           10,
+					EphemeralStorage: 10,
+					AllowedPodNumber: 10,
+					ScalarResources: map[corev1.ResourceName]int64{
+						"test.karmada.io/foo": 10,
+						"test.karmada.io/bar": 10,
+					},
+				},
+				rr: nil,
+			},
+			want: &Resource{
+				MilliCPU:         10,
+				Memory:           10,
+				EphemeralStorage: 10,
+				AllowedPodNumber: 10,
+				ScalarResources: map[corev1.ResourceName]int64{
+					"test.karmada.io/foo": 10,
+					"test.karmada.io/bar": 10,
+				},
+			},
+		},
+		{
+			name: "MilliCPU is not enough",
+			args: args{
+				r: &Resource{
+					MilliCPU:         10,
+					Memory:           10,
+					EphemeralStorage: 10,
+					AllowedPodNumber: 10,
+					ScalarResources: map[corev1.ResourceName]int64{
+						"test.karmada.io/foo": 10,
+						"test.karmada.io/bar": 10,
+					},
+				},
+				rr: &Resource{
+					MilliCPU:         99999,
+					Memory:           6,
+					EphemeralStorage: 6,
+					AllowedPodNumber: 6,
+					ScalarResources: map[corev1.ResourceName]int64{
+						"test.karmada.io/foo": 6,
+						"test.karmada.io/bar": 6,
+					},
+				},
+			},
+			want: &Resource{
+				MilliCPU:         0,
+				Memory:           4,
+				EphemeralStorage: 4,
+				AllowedPodNumber: 4,
+				ScalarResources: map[corev1.ResourceName]int64{
+					"test.karmada.io/foo": 4,
+					"test.karmada.io/bar": 4,
+				},
+			},
+		},
+		{
+			name: "Memory is not enough",
+			args: args{
+				r: &Resource{
+					MilliCPU:         10,
+					Memory:           10,
+					EphemeralStorage: 10,
+					AllowedPodNumber: 10,
+					ScalarResources: map[corev1.ResourceName]int64{
+						"test.karmada.io/foo": 10,
+						"test.karmada.io/bar": 10,
+					},
+				},
+				rr: &Resource{
+					MilliCPU:         6,
+					Memory:           99999,
+					EphemeralStorage: 6,
+					AllowedPodNumber: 6,
+					ScalarResources: map[corev1.ResourceName]int64{
+						"test.karmada.io/foo": 6,
+						"test.karmada.io/bar": 6,
+					},
+				},
+			},
+			want: &Resource{
+				MilliCPU:         4,
+				Memory:           0,
+				EphemeralStorage: 4,
+				AllowedPodNumber: 4,
+				ScalarResources: map[corev1.ResourceName]int64{
+					"test.karmada.io/foo": 4,
+					"test.karmada.io/bar": 4,
+				},
+			},
+		},
+		{
+			name: "EphemeralStorage is not enough",
+			args: args{
+				r: &Resource{
+					MilliCPU:         10,
+					Memory:           10,
+					EphemeralStorage: 10,
+					AllowedPodNumber: 10,
+					ScalarResources: map[corev1.ResourceName]int64{
+						"test.karmada.io/foo": 10,
+						"test.karmada.io/bar": 10,
+					},
+				},
+				rr: &Resource{
+					MilliCPU:         6,
+					Memory:           6,
+					EphemeralStorage: 99999,
+					AllowedPodNumber: 6,
+					ScalarResources: map[corev1.ResourceName]int64{
+						"test.karmada.io/foo": 6,
+						"test.karmada.io/bar": 6,
+					},
+				},
+			},
+			want: &Resource{
+				MilliCPU:         4,
+				Memory:           4,
+				EphemeralStorage: 0,
+				AllowedPodNumber: 4,
+				ScalarResources: map[corev1.ResourceName]int64{
+					"test.karmada.io/foo": 4,
+					"test.karmada.io/bar": 4,
+				},
+			},
+		},
+		{
+			name: "AllowedPodNumber is not enough",
+			args: args{
+				r: &Resource{
+					MilliCPU:         10,
+					Memory:           10,
+					EphemeralStorage: 10,
+					AllowedPodNumber: 10,
+					ScalarResources: map[corev1.ResourceName]int64{
+						"test.karmada.io/foo": 10,
+						"test.karmada.io/bar": 10,
+					},
+				},
+				rr: &Resource{
+					MilliCPU:         6,
+					Memory:           6,
+					EphemeralStorage: 6,
+					AllowedPodNumber: 99999,
+					ScalarResources: map[corev1.ResourceName]int64{
+						"test.karmada.io/foo": 6,
+						"test.karmada.io/bar": 6,
+					},
+				},
+			},
+			want: &Resource{
+				MilliCPU:         4,
+				Memory:           4,
+				EphemeralStorage: 4,
+				AllowedPodNumber: 0,
+				ScalarResources: map[corev1.ResourceName]int64{
+					"test.karmada.io/foo": 4,
+					"test.karmada.io/bar": 4,
+				},
+			},
+		},
+		{
+			name: "ScalarResources foo is not enough",
+			args: args{
+				r: &Resource{
+					MilliCPU:         10,
+					Memory:           10,
+					EphemeralStorage: 10,
+					AllowedPodNumber: 10,
+					ScalarResources: map[corev1.ResourceName]int64{
+						"test.karmada.io/foo": 10,
+						"test.karmada.io/bar": 10,
+					},
+				},
+				rr: &Resource{
+					MilliCPU:         6,
+					Memory:           6,
+					EphemeralStorage: 6,
+					AllowedPodNumber: 6,
+					ScalarResources: map[corev1.ResourceName]int64{
+						"test.karmada.io/foo": 9999,
+						"test.karmada.io/bar": 6,
+					},
+				},
+			},
+			want: &Resource{
+				MilliCPU:         4,
+				Memory:           4,
+				EphemeralStorage: 4,
+				AllowedPodNumber: 4,
+				ScalarResources: map[corev1.ResourceName]int64{
+					"test.karmada.io/foo": 0,
+					"test.karmada.io/bar": 4,
+				},
+			},
+		},
+		{
+			name: "ScalarResources bar is not enough",
+			args: args{
+				r: &Resource{
+					MilliCPU:         10,
+					Memory:           10,
+					EphemeralStorage: 10,
+					AllowedPodNumber: 10,
+					ScalarResources: map[corev1.ResourceName]int64{
+						"test.karmada.io/foo": 10,
+						"test.karmada.io/bar": 10,
+					},
+				},
+				rr: &Resource{
+					MilliCPU:         6,
+					Memory:           6,
+					EphemeralStorage: 6,
+					AllowedPodNumber: 6,
+					ScalarResources: map[corev1.ResourceName]int64{
+						"test.karmada.io/foo": 6,
+						"test.karmada.io/bar": 9999,
+					},
+				},
+			},
+			want: &Resource{
+				MilliCPU:         4,
+				Memory:           4,
+				EphemeralStorage: 4,
+				AllowedPodNumber: 4,
+				ScalarResources: map[corev1.ResourceName]int64{
+					"test.karmada.io/foo": 4,
+					"test.karmada.io/bar": 0,
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := tt.args.r.SubResource(tt.args.rr); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("got = %v, want = %v", tt.args.r, tt.want)
+			}
+		})
+	}
+}
+
+func TestResource_SetMaxResource(t *testing.T) {
+	type args struct {
+		r  *Resource
+		rl corev1.ResourceList
+	}
+	tests := []struct {
+		name string
+		args args
+		want *Resource
+	}{
+		{
+			name: "r is nil",
+			args: args{
+				r: nil,
+				rl: map[corev1.ResourceName]resource.Quantity{
+					corev1.ResourceCPU:              *resource.NewMilliQuantity(5, resource.DecimalSI),
+					corev1.ResourceMemory:           *resource.NewQuantity(5, resource.BinarySI),
+					corev1.ResourcePods:             *resource.NewQuantity(5, resource.DecimalSI),
+					corev1.ResourceEphemeralStorage: *resource.NewQuantity(5, resource.BinarySI),
+					"test.karmada.io/foo":           *resource.NewQuantity(5, resource.BinarySI),
+				},
+			},
+			want: nil,
+		},
+		{
+			name: "r is max",
+			args: args{
+				r: &Resource{
+					MilliCPU:         10,
+					Memory:           10,
+					EphemeralStorage: 10,
+					AllowedPodNumber: 10,
+					ScalarResources: map[corev1.ResourceName]int64{
+						"test.karmada.io/foo": 10,
+					},
+				},
+				rl: map[corev1.ResourceName]resource.Quantity{
+					corev1.ResourceCPU:              *resource.NewMilliQuantity(5, resource.DecimalSI),
+					corev1.ResourceMemory:           *resource.NewQuantity(5, resource.BinarySI),
+					corev1.ResourcePods:             *resource.NewQuantity(5, resource.DecimalSI),
+					corev1.ResourceEphemeralStorage: *resource.NewQuantity(5, resource.BinarySI),
+					"test.karmada.io/foo":           *resource.NewQuantity(5, resource.BinarySI),
+				},
+			},
+			want: &Resource{
+				MilliCPU:         10,
+				Memory:           10,
+				EphemeralStorage: 10,
+				AllowedPodNumber: 10,
+				ScalarResources: map[corev1.ResourceName]int64{
+					"test.karmada.io/foo": 10,
+				},
+			},
+		},
+		{
+			name: "rl is max",
+			args: args{
+				r: &Resource{
+					MilliCPU:         10,
+					Memory:           10,
+					EphemeralStorage: 10,
+					AllowedPodNumber: 10,
+					ScalarResources: map[corev1.ResourceName]int64{
+						"test.karmada.io/foo": 10,
+					},
+				},
+				rl: map[corev1.ResourceName]resource.Quantity{
+					corev1.ResourceCPU:              *resource.NewMilliQuantity(20, resource.DecimalSI),
+					corev1.ResourceMemory:           *resource.NewQuantity(20, resource.BinarySI),
+					corev1.ResourcePods:             *resource.NewQuantity(20, resource.DecimalSI),
+					corev1.ResourceEphemeralStorage: *resource.NewQuantity(20, resource.BinarySI),
+					"test.karmada.io/foo":           *resource.NewQuantity(20, resource.BinarySI),
+				},
+			},
+			want: &Resource{
+				MilliCPU:         20,
+				Memory:           20,
+				EphemeralStorage: 20,
+				AllowedPodNumber: 20,
+				ScalarResources: map[corev1.ResourceName]int64{
+					"test.karmada.io/foo": 20,
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			tt.args.r.SetMaxResource(tt.args.rl)
+			if !reflect.DeepEqual(tt.args.r, tt.want) {
+				t.Errorf("got %v, want %v", tt.args.r, tt.want)
+			}
+		})
+	}
+}
+
+func TestResource_ResourceList(t *testing.T) {
+	tests := []struct {
+		name     string
+		resource *Resource
+		want     corev1.ResourceList
+	}{
+		{
+			name:     "resource is empty",
+			resource: EmptyResource(),
+			want:     nil,
+		},
+		{
+			name: "resource list",
+			resource: &Resource{
+				MilliCPU:         10,
+				Memory:           10,
+				EphemeralStorage: 10,
+				AllowedPodNumber: 10,
+				ScalarResources: map[corev1.ResourceName]int64{
+					corev1.ResourceHugePagesPrefix + "foo": 10,
+					"test.karmada.io/bar":                  10,
+				},
+			},
+			want: map[corev1.ResourceName]resource.Quantity{
+				corev1.ResourceCPU:                     *resource.NewMilliQuantity(10, resource.DecimalSI),
+				corev1.ResourceMemory:                  *resource.NewQuantity(10, resource.BinarySI),
+				corev1.ResourcePods:                    *resource.NewQuantity(10, resource.DecimalSI),
+				corev1.ResourceEphemeralStorage:        *resource.NewQuantity(10, resource.BinarySI),
+				corev1.ResourceHugePagesPrefix + "foo": *resource.NewQuantity(10, resource.BinarySI),
+				"test.karmada.io/bar":                  *resource.NewQuantity(10, resource.DecimalSI),
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := tt.resource.ResourceList(); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("ResourceList() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestResource_MaxDivided(t *testing.T) {
+	type args struct {
+		r  *Resource
+		rl corev1.ResourceList
+	}
+	tests := []struct {
+		name string
+		args args
+		want int64
+	}{
+		{
+			name: "MaxDivided",
+			args: args{
+				r: &Resource{
+					MilliCPU:         100,
+					Memory:           100,
+					EphemeralStorage: 100,
+					AllowedPodNumber: 100,
+					ScalarResources: map[corev1.ResourceName]int64{
+						"test.karmada.io/foo": 100,
+					},
+				},
+				rl: map[corev1.ResourceName]resource.Quantity{
+					corev1.ResourceCPU:              *resource.NewMilliQuantity(10, resource.DecimalSI), // 10
+					corev1.ResourceMemory:           *resource.NewQuantity(5, resource.BinarySI),        // 20
+					corev1.ResourcePods:             *resource.NewQuantity(20, resource.DecimalSI),      //  4
+					corev1.ResourceEphemeralStorage: *resource.NewQuantity(15, resource.BinarySI),       // 6
+					"test.karmada.io/foo":           *resource.NewQuantity(18, resource.DecimalSI),      // 5
+				},
+			},
+			want: 5,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := tt.args.r.MaxDivided(tt.args.rl); got != tt.want {
+				t.Errorf("MaxDivided() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestResource_AddPodTemplateRequest(t *testing.T) {
+	type args struct {
+		podSpec *corev1.PodSpec
+	}
+	tests := []struct {
+		name string
+		args args
+		want *Resource
+	}{
+		{
+			name: "",
+			args: args{
+				podSpec: &corev1.PodSpec{
+					Containers: []corev1.Container{
+						{
+							Resources: corev1.ResourceRequirements{
+								Requests: corev1.ResourceList{
+									corev1.ResourceCPU:    *resource.NewMilliQuantity(10, resource.DecimalSI),
+									corev1.ResourceMemory: *resource.NewQuantity(10, resource.BinarySI),
+									"test.karmada.io/foo": *resource.NewQuantity(10, resource.DecimalSI),
+									"test.karmada.io/bar": *resource.NewQuantity(10, resource.DecimalSI),
+								},
+								Limits: corev1.ResourceList{
+									corev1.ResourceMemory: *resource.NewQuantity(99999, resource.BinarySI),
+									corev1.ResourcePods:   *resource.NewQuantity(10, resource.DecimalSI),
+									"test.karmada.io/bar": *resource.NewQuantity(99999, resource.DecimalSI),
+									"test.karmada.io/baz": *resource.NewQuantity(10, resource.DecimalSI),
+								},
+							},
+						},
+					},
+					InitContainers: []corev1.Container{
+						{
+							Resources: corev1.ResourceRequirements{
+								Requests: corev1.ResourceList{
+									corev1.ResourceCPU:    *resource.NewMilliQuantity(5, resource.DecimalSI),
+									corev1.ResourceMemory: *resource.NewQuantity(10, resource.BinarySI),
+									"test.karmada.io/foo": *resource.NewQuantity(5, resource.DecimalSI),
+									"test.karmada.io/bar": *resource.NewQuantity(10, resource.DecimalSI),
+								},
+								Limits: corev1.ResourceList{
+									corev1.ResourceMemory: *resource.NewQuantity(99999, resource.BinarySI),
+									corev1.ResourcePods:   *resource.NewQuantity(20, resource.DecimalSI),
+									"test.karmada.io/bar": *resource.NewQuantity(99999, resource.DecimalSI),
+									"test.karmada.io/baz": *resource.NewQuantity(20, resource.DecimalSI),
+								},
+							},
+						},
+					},
+					Overhead: map[corev1.ResourceName]resource.Quantity{
+						corev1.ResourceCPU:              *resource.NewMilliQuantity(5, resource.DecimalSI),
+						corev1.ResourceMemory:           *resource.NewQuantity(5, resource.BinarySI),
+						corev1.ResourceEphemeralStorage: *resource.NewQuantity(5, resource.BinarySI),
+						corev1.ResourcePods:             *resource.NewQuantity(5, resource.DecimalSI),
+						"test.karmada.io/foo":           *resource.NewQuantity(5, resource.DecimalSI),
+						"test.karmada.io/bar":           *resource.NewQuantity(5, resource.DecimalSI),
+						"test.karmada.io/baz":           *resource.NewQuantity(5, resource.DecimalSI),
+					},
+				},
+			},
+			want: &Resource{
+				MilliCPU:         15,
+				Memory:           15,
+				EphemeralStorage: 5,
+				AllowedPodNumber: 25,
+				ScalarResources: map[corev1.ResourceName]int64{
+					"test.karmada.io/foo": 15,
+					"test.karmada.io/bar": 15,
+					"test.karmada.io/baz": 25,
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			r := EmptyResource()
+			if got := r.AddPodTemplateRequest(tt.args.podSpec); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("AddPodTemplateRequest() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestResource_Clone(t *testing.T) {
+	tests := []struct {
+		name   string
+		caller *Resource
+		want   *Resource
+	}{
+		{
+			name:   "caller is nil",
+			caller: nil,
+			want:   nil,
+		},
+		{
+			name: "clone",
+			caller: &Resource{
+				MilliCPU:         1,
+				Memory:           2,
+				EphemeralStorage: 3,
+				AllowedPodNumber: 4,
+				ScalarResources: map[corev1.ResourceName]int64{
+					"test.karmada.io/foo": 5,
+					"test.karmada.io/bar": 6,
+					"test.karmada.io/baz": 7,
+				},
+			},
+			want: &Resource{
+				MilliCPU:         1,
+				Memory:           2,
+				EphemeralStorage: 3,
+				AllowedPodNumber: 4,
+				ScalarResources: map[corev1.ResourceName]int64{
+					"test.karmada.io/foo": 5,
+					"test.karmada.io/bar": 6,
+					"test.karmada.io/baz": 7,
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := tt.caller.Clone(); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("Clone() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}