diff --git a/paddle/operators/while_op.cc b/paddle/operators/while_op.cc
index 728ef6079465d57f54dab383aac5e2bb750fe113..65d827e0e0c5cfc3897c1fd0b971b766201cc1e2 100644
--- a/paddle/operators/while_op.cc
+++ b/paddle/operators/while_op.cc
@@ -25,12 +25,12 @@ namespace operators {
 using StepScopeVar = std::vector<framework::Scope *>;
 using LoDTensor = framework::LoDTensor;
 
-constexpr char kStepBlock[] = "sub_block";
-constexpr char kCondition[] = "Condition";
-constexpr char kStepScopes[] = "StepScopes";
-constexpr char kParameters[] = "X";
-constexpr char kParamGrads[] = "X@GRAD";
-constexpr char kOutputs[] = "Out";
+static constexpr char kStepBlock[] = "sub_block";
+static constexpr char kCondition[] = "Condition";
+static constexpr char kStepScopes[] = "StepScopes";
+static constexpr char kX[] = "X";
+static constexpr char kXGRAD[] = "X@GRAD";
+static constexpr char kOutputs[] = "Out";
 
 class WhileOp : public framework::OperatorBase {
  public:
@@ -67,7 +67,7 @@ class WhileOpMaker : public framework::OpProtoAndCheckerMaker {
  public:
   WhileOpMaker(OpProto *proto, OpAttrChecker *op_checker)
       : OpProtoAndCheckerMaker(proto, op_checker) {
-    AddInput(kParameters,
+    AddInput(kX,
              "A set of variables, which are required by operators inside the "
              "block of While Op.")
         .AsDuplicable();
@@ -158,8 +158,8 @@ class WhileGradOp : public framework::OperatorBase {
 
       executor.Run(*program, *cur_scope_iter, block->ID(), false);
 
-      auto &pg_names = Outputs(kParamGrads);
-      auto &p_names = Inputs(kParameters);
+      auto &pg_names = Outputs(kXGRAD);
+      auto &p_names = Inputs(kX);
       PADDLE_ENFORCE_EQ(pg_names.size(), p_names.size());
       for (size_t param_id = 0; param_id < pg_names.size(); ++param_id) {
         if (pg_names[param_id] == framework::kEmptyVarName) {
@@ -213,11 +213,11 @@ class WhileGradOpDescMaker : public framework::SingleGradOpDescMaker {
   std::unique_ptr<framework::OpDesc> Apply() const override {
     auto *grad = new framework::OpDesc();
     grad->SetType("while_grad");
-    grad->SetInput(kParameters, Input(kParameters));
+    grad->SetInput(kX, Input(kX));
 
     // Not all of IGs will be generated by inner gradient operators of while op.
     // Ignore IGs that is not generated by the inside block.
-    auto igs = InputGrad(kParameters, /*do not drop empty gradient*/ false);
+    auto igs = InputGrad(kX, /*do not drop empty gradient*/ false);
     std::unordered_set<std::string> all_outs;
     for (size_t i = 0; i < grad_block_[0]->OpSize(); ++i) {
       for (auto &oname : grad_block_[0]->Op(i)->OutputArgumentNames()) {
@@ -231,7 +231,7 @@ class WhileGradOpDescMaker : public framework::SingleGradOpDescMaker {
       }
     }
 
-    grad->SetOutput(framework::GradVarName(kParameters), igs);
+    grad->SetOutput(framework::GradVarName(kX), igs);
 
     grad->SetInput(kOutputs, Output(kOutputs));
 
@@ -240,7 +240,7 @@ class WhileGradOpDescMaker : public framework::SingleGradOpDescMaker {
     std::unordered_set<std::string> block_ins;
     auto *fwd_block = this->grad_block_[0]->ParentBlock();
     {
-      for (auto &p : Input(kParameters)) {
+      for (auto &p : Input(kX)) {
         block_ins.insert(p);
       }
       for (auto &o : Output(kOutputs)) {
@@ -288,8 +288,8 @@ class WhileGradOpVarTypeInference : public framework::VarTypeInference {
  public:
   void operator()(const framework::OpDesc &op_desc,
                   framework::BlockDesc *block) const override {
-    auto p_names = op_desc.Input(kParameters);
-    auto pg_names = op_desc.Output(framework::GradVarName(kParameters));
+    auto p_names = op_desc.Input(kX);
+    auto pg_names = op_desc.Output(framework::GradVarName(kX));
 
     for (size_t i = 0; i < p_names.size(); ++i) {
       auto &p_var = detail::Ref(block->FindVarRecursive(p_names[i]));
@@ -307,21 +307,21 @@ class WhileGradOpVarTypeInference : public framework::VarTypeInference {
 class WhileGradOpShapeInference : public framework::InferShapeBase {
  public:
   void operator()(framework::InferShapeContext *ctx) const override {
-    ctx->HasInputs(kParameters);
-    ctx->HasOutputs(framework::GradVarName(kParameters));
+    ctx->HasInputs(kX);
+    ctx->HasOutputs(framework::GradVarName(kX));
     ctx->HasInputs(kOutputs);
     ctx->HasInputs(framework::GradVarName(kOutputs));
 
-    auto p_names = ctx->Inputs(kParameters);
-    auto pg_names = ctx->Outputs(kParamGrads);
-    auto var_types = ctx->GetInputsVarType(kParameters);
+    auto p_names = ctx->Inputs(kX);
+    auto pg_names = ctx->Outputs(kXGRAD);
+    auto var_types = ctx->GetInputsVarType(kX);
     std::vector<std::string> names_to_set;
     std::vector<framework::DDim> dims_to_set;
     for (size_t i = 0; i < p_names.size(); ++i) {
       if (pg_names[i] == framework::kEmptyVarName) {
         continue;
       }
-      auto dims = ctx->GetInputsElementDim(kParameters, i);
+      auto dims = ctx->GetInputsElementDim(kX, i);
       if (var_types[i] == framework::proto::VarDesc::LOD_TENSOR) {
         names_to_set.push_back(pg_names[i]);
         dims_to_set.push_back(dims);