diff --git a/paddle/fluid/operators/reader/create_batch_reader_op.cc b/paddle/fluid/operators/reader/create_batch_reader_op.cc
index 1dbafd23e92732bdaf0d263a01e267227786d839..e17c2ffd39eea31fe85933eda144ab97cf8c3dd8 100644
--- a/paddle/fluid/operators/reader/create_batch_reader_op.cc
+++ b/paddle/fluid/operators/reader/create_batch_reader_op.cc
@@ -23,7 +23,7 @@ class BatchReader : public framework::DecoratedReader {
   BatchReader(const std::shared_ptr<ReaderBase>& reader, int batch_size,
               bool discard_leftover)
       : DecoratedReader(reader),
-        batch_size_(batch_size),
+        batch_size_(static_cast<size_t>(batch_size)),
         discard_leftover_(discard_leftover) {
     buffer_.reserve(batch_size_);
   }
@@ -31,7 +31,7 @@ class BatchReader : public framework::DecoratedReader {
   void ReadNextImpl(std::vector<framework::LoDTensor>* out) override;
 
  private:
-  int batch_size_;
+  size_t batch_size_;
   bool discard_leftover_;
   std::vector<std::vector<framework::LoDTensor>> buffer_;
 };
@@ -78,7 +78,7 @@ class CreateBatchReaderOpMaker : public DecoratedReaderMakerBase {
 void BatchReader::ReadNextImpl(std::vector<framework::LoDTensor>* out) {
   buffer_.clear();
   buffer_.reserve(batch_size_);
-  for (int i = 0; i < batch_size_; ++i) {
+  for (size_t i = 0; i < batch_size_; ++i) {
     buffer_.push_back(std::vector<framework::LoDTensor>());
     reader_->ReadNext(&buffer_.back());
     if (buffer_.back().empty()) {
@@ -95,9 +95,9 @@ void BatchReader::ReadNextImpl(std::vector<framework::LoDTensor>* out) {
     // if buffer_ is empty, the 'out' will return as an empty vector.
     return;
   }
-  int out_num = buffer_[0].size();
+  size_t out_num = buffer_[0].size();
   out->reserve(out_num);
-  for (int j = 0; j < out_num; ++j) {
+  for (size_t j = 0; j < out_num; ++j) {
     // Merge shape and check date type
     std::type_index batch_type = buffer_[0][j].type();
     framework::DDim batch_shape = buffer_[0][j].dims();