diff --git a/paddle/gserver/layers/PriorBox.cpp b/paddle/gserver/layers/PriorBox.cpp
index 337b9ba7bc..8faf032f55 100644
--- a/paddle/gserver/layers/PriorBox.cpp
+++ b/paddle/gserver/layers/PriorBox.cpp
@@ -69,7 +69,7 @@ bool PriorBoxLayer::init(const LayerMap& layerMap,
   if (maxSize_.size() > 0) CHECK_EQ(minSize_.size(), maxSize_.size());
 
   // flip aspect ratios
-  for (int index = 0; index < tmp.size(); index++) {
+  for (unsigned index = 0; index < tmp.size(); index++) {
     real ar = tmp[index];
     if (fabs(ar - 1.) < 1e-6) continue;
     aspectRatio_.push_back(ar);
diff --git a/paddle/operators/ctc_align_op.h b/paddle/operators/ctc_align_op.h
index 589413feb3..fed89aa1e8 100644
--- a/paddle/operators/ctc_align_op.h
+++ b/paddle/operators/ctc_align_op.h
@@ -51,7 +51,7 @@ class CTCAlignKernel : public framework::OpKernel<T> {
       T prev_token = -1;
       for (size_t i = input_lod[level][seq_idx];
            i < input_lod[level][seq_idx + 1]; ++i) {
-        if (input_data[i] != blank &&
+        if ((unsigned)input_data[i] != blank &&
             !(merge_repeated && input_data[i] == prev_token)) {
           output_data[output_idx] = input_data[i];
           ++output_idx;
diff --git a/paddle/operators/sequence_reshape_op.h b/paddle/operators/sequence_reshape_op.h
index c6f528ab8a..aaae7ab292 100644
--- a/paddle/operators/sequence_reshape_op.h
+++ b/paddle/operators/sequence_reshape_op.h
@@ -35,7 +35,7 @@ class SequenceReshapeKernel : public framework::OpKernel<T> {
     PADDLE_ENFORCE_EQ(in_lod.size(), 1UL,
                       "Only support one level sequence now.");
     PADDLE_ENFORCE_EQ(
-        in_dims[0], in_lod[0].back(),
+        (uint64_t)in_dims[0], in_lod[0].back(),
         "Inconsistent size between X.shape[0] and X.lod()[0].back().");
 
     auto in_lod_l0 = in_lod[0];