diff --git a/doc/design/cluster_train/trainer.md b/doc/design/cluster_train/trainer.md
index c9c090dc984866bcc769fc45c902865610d7e545..bcb4a9c09dccc2961edb480c399fd41be761bf02 100644
--- a/doc/design/cluster_train/trainer.md
+++ b/doc/design/cluster_train/trainer.md
@@ -57,9 +57,15 @@ type UpdateRule struct {
 // closing the send channel.
 func (*PServerClient) ParamInitChan() (send chan<- Parameter, err error)
 
-// SendGrad sends gradients to parameter servers.
+// SendGrad sends gradients to parameter servers for updating parameters.
 func (*PServerClient) SendGrad(method UpdateMethod, grads []Gradient) error
 
+// SetParam sets parameters.
+//
+// SetParam can be used for the parameters that are not suitable for updating
+// using gradients.
+func (*PServerClient) SetParam(params []Paramter) error
+
 // GetParam gets parameters from parameter servers.
 func (*PServerClient) GetParam(names []string) ([]Parameter, error)