diff --git a/paddle/gserver/gradientmachines/GradientMachine.h b/paddle/gserver/gradientmachines/GradientMachine.h
index 873b89e3fc6ad63f1dce4c823884ddb42aec25ec..26ce340aa69b4ab5fc888e5ba76d005d674a80b9 100644
--- a/paddle/gserver/gradientmachines/GradientMachine.h
+++ b/paddle/gserver/gradientmachines/GradientMachine.h
@@ -181,7 +181,7 @@ public:
   /**
    * Create an evaluator which can be used for eval()
    */
-  virtual Evaluator* makeEvaluator() = 0;
+  virtual Evaluator* makeEvaluator() const = 0;
 
   /**
    * evaluate using the given evaluator
diff --git a/paddle/gserver/gradientmachines/MultiGradientMachine.cpp b/paddle/gserver/gradientmachines/MultiGradientMachine.cpp
index a34316c57adf3b3c51b4d12187db62d2ad65c8ea..bd51507a291a18ab87735682d99bd6ecb01a3490 100644
--- a/paddle/gserver/gradientmachines/MultiGradientMachine.cpp
+++ b/paddle/gserver/gradientmachines/MultiGradientMachine.cpp
@@ -327,7 +327,7 @@ void MultiGradientMachine::finish() {
   }
 }
 
-Evaluator* MultiGradientMachine::makeEvaluator() {
+Evaluator* MultiGradientMachine::makeEvaluator() const {
   return threads_[0]->getGradientMachine()->makeEvaluator();
 }
 
diff --git a/paddle/gserver/gradientmachines/MultiGradientMachine.h b/paddle/gserver/gradientmachines/MultiGradientMachine.h
index f2b074e393916cc7bff641819ea299fb45ff3b92..9be15ef4bcf34f26b7eceb9047252e537f20a4a8 100644
--- a/paddle/gserver/gradientmachines/MultiGradientMachine.h
+++ b/paddle/gserver/gradientmachines/MultiGradientMachine.h
@@ -193,7 +193,7 @@ public:
 
   virtual void finish();
 
-  virtual Evaluator* makeEvaluator();
+  virtual Evaluator* makeEvaluator() const;
 
   virtual void eval(Evaluator* evaluator) const;
 
diff --git a/paddle/gserver/gradientmachines/MultiNetwork.cpp b/paddle/gserver/gradientmachines/MultiNetwork.cpp
index 33100c842b4dadb3dffa3b9e54166bec9089a3c9..933144b5bd65a4577827e565aa9724a1964dd5a6 100644
--- a/paddle/gserver/gradientmachines/MultiNetwork.cpp
+++ b/paddle/gserver/gradientmachines/MultiNetwork.cpp
@@ -172,7 +172,7 @@ protected:
   std::vector<std::unique_ptr<Evaluator>> evaluators_;
 };
 
-Evaluator* MultiNetwork::makeEvaluator() {
+Evaluator* MultiNetwork::makeEvaluator() const {
   MultiCombinedEvaluator* multiCombinedEvaluator = new MultiCombinedEvaluator();
   for (size_t i = 0; i < subNetworks_.size(); i++) {
     std::unique_ptr<Evaluator> evaluator(subNetworks_[i]->makeEvaluator());
diff --git a/paddle/gserver/gradientmachines/MultiNetwork.h b/paddle/gserver/gradientmachines/MultiNetwork.h
index 93b8b5d2bac7dee71672010b17c065b80df7477c..ce024659ec366afde5262d1c7a24949f74bbd2ab 100644
--- a/paddle/gserver/gradientmachines/MultiNetwork.h
+++ b/paddle/gserver/gradientmachines/MultiNetwork.h
@@ -46,7 +46,7 @@ public:
 
   virtual void onPassEnd();
 
-  virtual Evaluator* makeEvaluator();
+  virtual Evaluator* makeEvaluator() const;
 
   virtual void eval(Evaluator* evaluator) const;
 
diff --git a/paddle/gserver/gradientmachines/NeuralNetwork.cpp b/paddle/gserver/gradientmachines/NeuralNetwork.cpp
index 98d0bcac7971f7bb81379f7fe774fd74edaa30da..22051e07ee0026bc3c44a8767e265a56b415b8e4 100644
--- a/paddle/gserver/gradientmachines/NeuralNetwork.cpp
+++ b/paddle/gserver/gradientmachines/NeuralNetwork.cpp
@@ -348,7 +348,7 @@ protected:
   std::vector<std::unique_ptr<Evaluator>> evaluators_;
 };
 
-Evaluator* NeuralNetwork::makeEvaluator() {
+Evaluator* NeuralNetwork::makeEvaluator() const {
   CombinedEvaluator* combinedEvaluator = new CombinedEvaluator();
   auto subModelConfig = std::find_if(config_.sub_models().begin(),
                                      config_.sub_models().end(),
diff --git a/paddle/gserver/gradientmachines/NeuralNetwork.h b/paddle/gserver/gradientmachines/NeuralNetwork.h
index 3a07e0bc9f998af5b757805c07da83e70d143db8..25af4abcf81700e200feea806fa3daed19df1275 100644
--- a/paddle/gserver/gradientmachines/NeuralNetwork.h
+++ b/paddle/gserver/gradientmachines/NeuralNetwork.h
@@ -96,7 +96,7 @@ public:
 
   virtual void onPassEnd();
 
-  virtual Evaluator* makeEvaluator();
+  virtual Evaluator* makeEvaluator() const;
 
   virtual void eval(Evaluator* evaluator) const;
   virtual void resetState();