diff --git a/paddle/fluid/inference/tensorrt/plugin/instance_norm_op_plugin.h b/paddle/fluid/inference/tensorrt/plugin/instance_norm_op_plugin.h
index 3f5023f369510b5d89a9896605e77a2b152bdb39..ec1d8e6517ed0d6fbc00c5f54d6b4af404cc60d6 100644
--- a/paddle/fluid/inference/tensorrt/plugin/instance_norm_op_plugin.h
+++ b/paddle/fluid/inference/tensorrt/plugin/instance_norm_op_plugin.h
@@ -41,7 +41,8 @@ class InstanceNormPlugin : public PluginTensorRT {
  protected:
   size_t getSerializationSize() override {
     return getBaseSerializationSize() + SerializedSize(eps_) +
-           SerializedSize(scale_) + SerializedSize(bias_);
+           SerializedSize(scale_) + SerializedSize(bias_) +
+           SerializedSize(getPluginType());
   }
 
   // TRT will call this func when we need to serialize the configuration of