diff --git a/src/main/java/org/tikv/common/apiversion/CodecUtils.java b/src/main/java/org/tikv/common/apiversion/CodecUtils.java
index 1c6cfea9fa..a2b0725be5 100644
--- a/src/main/java/org/tikv/common/apiversion/CodecUtils.java
+++ b/src/main/java/org/tikv/common/apiversion/CodecUtils.java
@@ -23,7 +23,7 @@ import org.tikv.common.codec.CodecDataInput;
 import org.tikv.common.codec.CodecDataOutput;
 
 // TODO(iosmanthus): use ByteString.wrap to avoid once more copying.
-class CodecUtils {
+public class CodecUtils {
   public static ByteString encode(ByteString key) {
     CodecDataOutput cdo = new CodecDataOutput();
     BytesCodec.writeBytes(cdo, key.toByteArray());
diff --git a/src/main/java/org/tikv/common/apiversion/RequestKeyV2Codec.java b/src/main/java/org/tikv/common/apiversion/RequestKeyV2Codec.java
index 11db11c641..ab86fb5e02 100644
--- a/src/main/java/org/tikv/common/apiversion/RequestKeyV2Codec.java
+++ b/src/main/java/org/tikv/common/apiversion/RequestKeyV2Codec.java
@@ -81,22 +81,21 @@ public class RequestKeyV2Codec implements RequestKeyCodec {
 
     if (!start.isEmpty()) {
       start = CodecUtils.decode(start);
-      if (ByteString.unsignedLexicographicalComparator().compare(start, keyPrefix) < 0) {
-        start = ByteString.EMPTY;
-      } else {
-        start = decodeKey(start);
-      }
     }
 
     if (!end.isEmpty()) {
       end = CodecUtils.decode(end);
-      if (ByteString.unsignedLexicographicalComparator().compare(end, infiniteEndKey) >= 0) {
-        end = ByteString.EMPTY;
-      } else {
-        end = decodeKey(end);
-      }
     }
 
+    if (ByteString.unsignedLexicographicalComparator().compare(start, infiniteEndKey) >= 0
+        || (!end.isEmpty()
+            && ByteString.unsignedLexicographicalComparator().compare(end, keyPrefix) <= 0)) {
+      throw new IllegalArgumentException("region out of keyspace" + region.toString());
+    }
+
+    start = start.startsWith(keyPrefix) ? start.substring(keyPrefix.size()) : ByteString.EMPTY;
+    end = end.startsWith(keyPrefix) ? end.substring(keyPrefix.size()) : ByteString.EMPTY;
+
     return builder.setStartKey(start).setEndKey(end).build();
   }
 }
diff --git a/src/test/java/org/tikv/common/apiversion/RequestKeyCodecTest.java b/src/test/java/org/tikv/common/apiversion/RequestKeyCodecTest.java
index 871a20cdf2..60ffa53e70 100644
--- a/src/test/java/org/tikv/common/apiversion/RequestKeyCodecTest.java
+++ b/src/test/java/org/tikv/common/apiversion/RequestKeyCodecTest.java
@@ -17,8 +17,7 @@
 
 package org.tikv.common.apiversion;
 
-import static org.junit.Assert.assertArrayEquals;
-import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.*;
 
 import com.google.common.collect.ImmutableList;
 import com.google.protobuf.ByteString;
@@ -177,5 +176,79 @@ public class RequestKeyCodecTest {
     decoded = v2.decodeRegion(region);
     assertEquals(start, decoded.getStartKey());
     assertEquals(ByteString.EMPTY, decoded.getEndKey());
+
+    // test region out of keyspace
+    region =
+        Region.newBuilder()
+            .setStartKey(ByteString.EMPTY)
+            .setEndKey(CodecUtils.encode(v2.keyPrefix))
+            .build();
+
+    try {
+      decoded = v2.decodeRegion(region);
+      fail();
+    } catch (Exception ignored) {
+    }
+
+    region =
+        Region.newBuilder()
+            .setStartKey(CodecUtils.encode(v2.infiniteEndKey))
+            .setEndKey(ByteString.EMPTY)
+            .build();
+    try {
+      decoded = v2.decodeRegion(region);
+      fail();
+    } catch (Exception ignored) {
+    }
+
+    // case: regionStartKey == "" < keyPrefix < regionEndKey < infiniteEndKey
+    region =
+        Region.newBuilder()
+            .setStartKey(ByteString.EMPTY)
+            .setEndKey(CodecUtils.encode(v2.keyPrefix.concat(ByteString.copyFromUtf8("0"))))
+            .build();
+    decoded = v2.decodeRegion(region);
+    assertTrue(decoded.getStartKey().isEmpty());
+    assertEquals(ByteString.copyFromUtf8("0"), decoded.getEndKey());
+
+    // case: "" < regionStartKey < keyPrefix < regionEndKey < infiniteEndKey < ""
+    region =
+        Region.newBuilder()
+            .setStartKey(CodecUtils.encode(ByteString.copyFromUtf8("m_123")))
+            .setEndKey(CodecUtils.encode(v2.keyPrefix.concat(ByteString.copyFromUtf8("0"))))
+            .build();
+    decoded = v2.decodeRegion(region);
+    assertEquals(ByteString.EMPTY, decoded.getStartKey());
+    assertEquals(ByteString.copyFromUtf8("0"), decoded.getEndKey());
+
+    // case: "" < regionStartKey < keyPrefix < infiniteEndKey < regionEndKey < ""
+    region =
+        Region.newBuilder()
+            .setStartKey(CodecUtils.encode(ByteString.copyFromUtf8("m_123")))
+            .setEndKey(CodecUtils.encode(v2.infiniteEndKey.concat(ByteString.copyFromUtf8("0"))))
+            .build();
+    decoded = v2.decodeRegion(region);
+    assertEquals(ByteString.EMPTY, decoded.getStartKey());
+    assertEquals(ByteString.EMPTY, decoded.getEndKey());
+
+    // case: keyPrefix < regionStartKey <  infiniteEndKey < regionEndKey < ""
+    region =
+        Region.newBuilder()
+            .setStartKey(CodecUtils.encode(v2.keyPrefix.concat(ByteString.copyFromUtf8("0"))))
+            .setEndKey(CodecUtils.encode(v2.infiniteEndKey.concat(ByteString.copyFromUtf8("0"))))
+            .build();
+    decoded = v2.decodeRegion(region);
+    assertEquals(ByteString.copyFromUtf8("0"), decoded.getStartKey());
+    assertTrue(decoded.getEndKey().isEmpty());
+
+    // case: keyPrefix < regionStartKey <  infiniteEndKey < regionEndKey == ""
+    region =
+        Region.newBuilder()
+            .setStartKey(CodecUtils.encode(v2.keyPrefix.concat(ByteString.copyFromUtf8("0"))))
+            .setEndKey(ByteString.EMPTY)
+            .build();
+    decoded = v2.decodeRegion(region);
+    assertEquals(ByteString.copyFromUtf8("0"), decoded.getStartKey());
+    assertTrue(decoded.getEndKey().isEmpty());
   }
 }