diff --git a/paddle/framework/mixed_vector.h b/paddle/framework/mixed_vector.h
index 0e0e23958602343f8e0106e3a88eaac9c6d71066..85caac8dcd9ede4fe997e2fd246d1421aa73c80a 100644
--- a/paddle/framework/mixed_vector.h
+++ b/paddle/framework/mixed_vector.h
@@ -34,18 +34,6 @@ namespace framework {
 
 template <typename T>
 class Vector : public std::vector<T> {
- public:
-  /* NOTE(dzhwinter):
-   * Data always store and modified on Host.
-   * If the data is modified when use cuda_data interface,
-   * You need to call the CopyFromCUDA explicitly to synchronize data.
-   *
-   */
-  enum class kDataPosition {
-    kDataOnHost = 0,
-    kDataOnDevice = 1,
-  };
-
  public:
   using std::vector<T>::vector;
 
@@ -55,11 +43,12 @@ class Vector : public std::vector<T> {
   virtual ~Vector() {
 #ifdef PADDLE_WITH_CUDA
     if (cuda_ptr_ != nullptr) {
-      memory::Free<platform::CUDAPlace>(place_, static_cast<void *>(cuda_ptr_));
+      memory::Free<platform::CUDAPlace>(place_, cuda_ptr_);
     }
 #endif
   }
 
+  /* Get device vector */
   T *cuda_data() {
     CopyToCUDA();
     PADDLE_ENFORCE_NOT_NULL(
@@ -67,81 +56,73 @@ class Vector : public std::vector<T> {
     return static_cast<T *>(cuda_ptr_);
   }
 
+  /* Get host vector */
   T *data() { return std::vector<T>::data(); }
-
   const T *data() const { return std::vector<T>::data(); }
 
+  /* Synchronize host vector to device vector */
   void CopyToCUDA();
-
+  /* Synchronize device vector to host vector */
   void CopyFromCUDA();
-
+  /* Switch device vector location */
   void CopyToPeer(platform::Place);
 
  private:
   void *cuda_ptr_ = nullptr;
-  size_t cuda_size_ = 0;
-  /*The DataPosition is unused now,
-    if we want support random access from cpu and cuda,
-    we need to overload all the vector method */
-
-  kDataPosition position_ = kDataPosition::kDataOnHost;
+  size_t cuda_size_ = 0;  // device vector numel
   platform::CUDAPlace place_;
 };
 
 template <typename T>
 void Vector<T>::CopyToCUDA() {
 #ifdef PADDLE_WITH_CUDA
-  if (cuda_ptr_ == nullptr) {
+  if (cuda_size_ < this->size()) {
+    if (cuda_ptr_ != nullptr) {
+      memory::Free<platform::CUDAPlace>(place_, cuda_ptr_);
+    }
     cuda_ptr_ =
         memory::Alloc<platform::CUDAPlace>(place_, this->size() * sizeof(T));
   }
+  cuda_size_ = this->size();
   platform::DeviceContextPool &pool = platform::DeviceContextPool::Instance();
-  auto *cuda_ctx = pool.GetByPlace(place_);
-
-  memory::Copy(place_, static_cast<void *>(cuda_ptr_), platform::CPUPlace(),
+  auto *ctx = pool.GetByPlace(place_);
+  memory::Copy(place_, cuda_ptr_, platform::CPUPlace(),
                static_cast<const void *>(this->data()),
-               this->size() * sizeof(T), cuda_ctx->stream());
-  cuda_ctx->Wait();
-
-  cuda_size_ = this->size();
+               this->size() * sizeof(T), ctx->stream());
+  ctx->Wait();
 #endif
 }
 
 template <typename T>
 void Vector<T>::CopyFromCUDA() {
 #ifdef PADDLE_WITH_CUDA
-  platform::DeviceContextPool &pool = platform::DeviceContextPool::Instance();
-  auto *cuda_ctx = pool.GetByPlace(place_);
   if (cuda_ptr_ == nullptr) {
-    LOG(WARNING) << "No uncommited cuda data.";
+    LOG(WARNING) << "No uncommitted cuda data.";
     return;
   }
   this->resize(cuda_size_);
+  platform::DeviceContextPool &pool = platform::DeviceContextPool::Instance();
+  auto *ctx = pool.GetByPlace(place_);
   memory::Copy(platform::CPUPlace(), static_cast<void *>(this->data()), place_,
                static_cast<const void *>(cuda_ptr_), this->size() * sizeof(T),
-               cuda_ctx->stream());
-  cuda_ctx->Wait();
-
+               ctx->stream());
+  ctx->Wait();
 #endif
 }
 
 template <typename T>
 void Vector<T>::CopyToPeer(platform::Place peer_place) {
-  if (platform::is_cpu_place(peer_place)) {
-    return;
-  }
 #ifdef PADDLE_WITH_CUDA
-  auto *cuda_ctx = platform::DeviceContextPool::Instance().GetByPlace(place_);
-  void *peer_cuda_ptr_ = memory::Alloc<platform::CUDAPlace>(
+  auto *ctx = platform::DeviceContextPool::Instance().GetByPlace(place_);
+  void *peer_cuda_ptr = memory::Alloc<platform::CUDAPlace>(
       boost::get<platform::CUDAPlace>(peer_place), this->size() * sizeof(T));
-  memory::Copy(boost::get<platform::CUDAPlace>(peer_place),
-               static_cast<void *>(peer_cuda_ptr_), place_,
-               static_cast<const void *>(cuda_ptr_), this->size() * sizeof(T),
-               cuda_ctx->stream());
-  cuda_ctx->Wait();
-  memory::Free<platform::CUDAPlace>(place_, static_cast<void *>(cuda_ptr_));
+  memory::Copy(boost::get<platform::CUDAPlace>(peer_place), peer_cuda_ptr,
+               place_, cuda_ptr_, this->size() * sizeof(T), ctx->stream());
+  ctx->Wait();
+
+  memory::Free<platform::CUDAPlace>(place_, cuda_ptr_);
   place_ = boost::get<platform::CUDAPlace>(peer_place);
-  cuda_ptr_ = peer_cuda_ptr_;
+  cuda_ptr_ = peer_cuda_ptr;
 #endif
 }