diff --git a/paddle/fluid/framework/parallel_executor.h b/paddle/fluid/framework/parallel_executor.h
index 47e0005e58d916c15c87a2e9d3cf5f8e8c550102..f67b9266949dedf90cccbd2398e2dda66e8f21c4 100644
--- a/paddle/fluid/framework/parallel_executor.h
+++ b/paddle/fluid/framework/parallel_executor.h
@@ -52,8 +52,7 @@ class ParallelExecutor {
  private:
   std::vector<framework::Executor> exes_;
   std::vector<framework::Scope*> scopes_;
-  AllReduceCallBack all_reduce_callbacks_;
-  std::unordered_set<std::string> params_;  // where to initilize it?
+  std::vector<AllReduceCallBack> all_reduce_callbacks_;
   platform::Communicator nccl_com_;
 };