diff --git a/docs/admin/network-plugins.md b/docs/admin/network-plugins.md
index eadbd67120..62419574e3 100644
--- a/docs/admin/network-plugins.md
+++ b/docs/admin/network-plugins.md
@@ -42,6 +42,8 @@ If there are multiple CNI configuration files in the directory, the first one in
 
 In addition to the CNI plugin specified by the configuration file, Kubernetes requires the standard CNI `lo` plugin, at minimum version 0.2.0
 
+Limitation: Due to [#31307](https://github.com/kubernetes/kubernetes/issues/31307), `HostPort` won't work with CNI networking plugin at the moment. That means all `hostPort` attribute in pod would be simply ignored.
+
 ### kubenet
 
 Kubenet is a very basic, simple network plugin, on Linux only.  It does not, of itself, implement more advanced features like cross-node networking or network policy.  It is typically used together with a cloud provider that sets up routing rules for communication between nodes, or in single-node environments.
@@ -76,4 +78,4 @@ This option is provided to the network-plugin; currently **only kubenet supports
 * `--network-plugin=exec` specifies that we use the `exec` plugin, with executables located in `--network-plugin-dir`.
 * `--network-plugin=cni` specifies that we use the `cni` network plugin with actual CNI plugin binaries located in `--cni-bin-dir` (default `/opt/cni/bin`) and CNI plugin configuration located in `--cni-conf-dir` (default `/etc/cni/net.d`).
 * `--network-plugin=kubenet` specifies that we use the `kubenet` network plugin with CNI `bridge` and `host-local` plugins placed in `/opt/cni/bin` or `network-plugin-dir`.
-* `--network-plugin-mtu=9001` specifies the MTU to use, currently only used by the `kubenet` network plugin.
\ No newline at end of file
+* `--network-plugin-mtu=9001` specifies the MTU to use, currently only used by the `kubenet` network plugin.