diff --git a/lite/api/light_api.cc b/lite/api/light_api.cc
index 7a7f870a9ac38e4103f3f8a7c6b95a98bb6722db..65ce77276afdb4c3b7a7247cdb8ae120497d8145 100644
--- a/lite/api/light_api.cc
+++ b/lite/api/light_api.cc
@@ -82,7 +82,7 @@ Tensor* LightPredictor::GetInputByName(const std::string& name) {
   if (element == input_names_.end()) {
     LOG(ERROR) << "Model do not have input named with: [" << name
                << "], model's inputs include:";
-    for (int i = 0; i < input_names_.size(); i++) {
+    for (size_t i = 0; i < input_names_.size(); i++) {
       LOG(ERROR) << "[" << input_names_[i] << "]";
     }
     return nullptr;
@@ -114,7 +114,7 @@ void LightPredictor::PrepareFeedFetch() {
   auto current_block = cpp_program_desc_.GetBlock<cpp::BlockDesc>(0);
   std::vector<cpp::OpDesc*> feeds;
   std::vector<cpp::OpDesc*> fetchs;
-  for (int i = 0; i < current_block->OpsSize(); i++) {
+  for (size_t i = 0; i < current_block->OpsSize(); i++) {
     auto op = current_block->GetOp<cpp::OpDesc>(i);
     if (op->Type() == "feed") {
       feeds.push_back(op);
@@ -124,11 +124,11 @@ void LightPredictor::PrepareFeedFetch() {
   }
   input_names_.resize(feeds.size());
   output_names_.resize(fetchs.size());
-  for (int i = 0; i < feeds.size(); i++) {
+  for (size_t i = 0; i < feeds.size(); i++) {
     input_names_[feeds[i]->GetAttr<int>("col")] =
         feeds[i]->Output("Out").front();
   }
-  for (int i = 0; i < fetchs.size(); i++) {
+  for (size_t i = 0; i < fetchs.size(); i++) {
     output_names_[fetchs[i]->GetAttr<int>("col")] =
         fetchs[i]->Input("X").front();
   }
diff --git a/lite/api/light_api_test.cc b/lite/api/light_api_test.cc
index b49ff8b80c936b93acd630c6e0cde03df8b22ee4..08779c0b5c9802ebc5095241b2543d8724981dff 100644
--- a/lite/api/light_api_test.cc
+++ b/lite/api/light_api_test.cc
@@ -37,11 +37,11 @@ TEST(LightAPI, load) {
   const std::vector<std::string> inputs = predictor.GetInputNames();
 
   LOG(INFO) << "input size: " << inputs.size();
-  for (int i = 0; i < inputs.size(); i++) {
+  for (size_t i = 0; i < inputs.size(); i++) {
     LOG(INFO) << "inputnames: " << inputs[i];
   }
   const std::vector<std::string> outputs = predictor.GetOutputNames();
-  for (int i = 0; i < outputs.size(); i++) {
+  for (size_t i = 0; i < outputs.size(); i++) {
     LOG(INFO) << "outputnames: " << outputs[i];
   }
 
diff --git a/lite/api/lite_multithread_test.cc b/lite/api/lite_multithread_test.cc
index 12559d171ff3df808cf252e8e09c652246902abf..33c0a94cf1a254e42c47aa462c5cfe12e386a87e 100644
--- a/lite/api/lite_multithread_test.cc
+++ b/lite/api/lite_multithread_test.cc
@@ -293,13 +293,13 @@ int main(int argc, char** argv) {
 
   std::vector<std::string> str_input_shapes = split_string(FLAGS_input_shape);
   std::vector<std::vector<int64_t>> input_shapes;
-  for (int i = 0; i < str_input_shapes.size(); ++i) {
+  for (size_t i = 0; i < str_input_shapes.size(); ++i) {
     input_shapes.push_back(get_shape(str_input_shapes[i]));
   }
   std::vector<std::string> str_input_shapes_0 =
       split_string(FLAGS_input_shape_0);
   std::vector<std::vector<int64_t>> input_shapes_0;
-  for (int i = 0; i < str_input_shapes_0.size(); ++i) {
+  for (size_t i = 0; i < str_input_shapes_0.size(); ++i) {
     input_shapes_0.push_back(get_shape(str_input_shapes_0[i]));
   }
 
diff --git a/lite/api/model_test.cc b/lite/api/model_test.cc
index 898521a6fc0bf6d1f02ffa9a04f4dc6c4ea02612..f61ed9b4c38fcc3a6fe33fd26d6d3a80edcb9373 100644
--- a/lite/api/model_test.cc
+++ b/lite/api/model_test.cc
@@ -204,7 +204,7 @@ int main(int argc, char** argv) {
   LOG(INFO) << "input shapes: " << FLAGS_input_shape;
   std::vector<std::string> str_input_shapes = split_string(FLAGS_input_shape);
   std::vector<std::vector<int64_t>> input_shapes;
-  for (int i = 0; i < str_input_shapes.size(); ++i) {
+  for (size_t i = 0; i < str_input_shapes.size(); ++i) {
     LOG(INFO) << "input shape: " << str_input_shapes[i];
     input_shapes.push_back(get_shape(str_input_shapes[i]));
   }
diff --git a/lite/api/model_test_classify.cc b/lite/api/model_test_classify.cc
index 375d249476bf5323d69ea41c3f11d07e9c8bc711..5d2011e29bfdeb166ae1ad202d96a204893888b0 100644
--- a/lite/api/model_test_classify.cc
+++ b/lite/api/model_test_classify.cc
@@ -310,7 +310,7 @@ int main(int argc, char** argv) {
   LOG(INFO) << "input shapes: " << FLAGS_input_shape;
   std::vector<std::string> str_input_shapes = split_string(FLAGS_input_shape);
   std::vector<std::vector<int64_t>> input_shapes;
-  for (int i = 0; i < str_input_shapes.size(); ++i) {
+  for (size_t i = 0; i < str_input_shapes.size(); ++i) {
     LOG(INFO) << "input shape: " << str_input_shapes[i];
     input_shapes.push_back(get_shape(str_input_shapes[i]));
   }
diff --git a/lite/api/model_test_detection.cc b/lite/api/model_test_detection.cc
index f9be12b2c78c623a2b2c9852850576cc11815bd3..f059aca6330613f66fa93267c0c594cfba6d8833 100644
--- a/lite/api/model_test_detection.cc
+++ b/lite/api/model_test_detection.cc
@@ -114,7 +114,7 @@ void detect_object(const float* dout,
   }
   std::string name = FLAGS_out_txt + "_accu.txt";
   FILE* fp = fopen(name.c_str(), "w");
-  for (int i = 0; i < objects.size(); ++i) {
+  for (size_t i = 0; i < objects.size(); ++i) {
     Object object = objects.at(i);
     if (object.prob > thresh && object.x > 0 && object.y > 0 &&
         object.width > 0 && object.height > 0) {
@@ -324,7 +324,7 @@ int main(int argc, char** argv) {
   LOG(INFO) << "input shapes: " << FLAGS_input_shape;
   std::vector<std::string> str_input_shapes = split_string(FLAGS_input_shape);
   std::vector<std::vector<int64_t>> input_shapes;
-  for (int i = 0; i < str_input_shapes.size(); ++i) {
+  for (size_t i = 0; i < str_input_shapes.size(); ++i) {
     LOG(INFO) << "input shape: " << str_input_shapes[i];
     input_shapes.push_back(get_shape(str_input_shapes[i]));
   }
diff --git a/lite/api/paddle_api_test.cc b/lite/api/paddle_api_test.cc
index 9b8384f2823ee121aa8bb505dd135735d9f96774..832867df079efa1baebf08da4c0d8e37958460f1 100644
--- a/lite/api/paddle_api_test.cc
+++ b/lite/api/paddle_api_test.cc
@@ -36,11 +36,11 @@ TEST(CxxApi, run) {
 
   auto inputs = predictor->GetInputNames();
   LOG(INFO) << "input size: " << inputs.size();
-  for (int i = 0; i < inputs.size(); i++) {
+  for (size_t i = 0; i < inputs.size(); i++) {
     LOG(INFO) << "inputnames: " << inputs[i];
   }
   auto outputs = predictor->GetOutputNames();
-  for (int i = 0; i < outputs.size(); i++) {
+  for (size_t i = 0; i < outputs.size(); i++) {
     LOG(INFO) << "outputnames: " << outputs[i];
   }
   auto input_tensor = predictor->GetInputByName(inputs[0]);
diff --git a/lite/api/test_googlenet_lite.cc b/lite/api/test_googlenet_lite.cc
index 8ff7a49af9cbce09d205bb8633a913410beb91c3..f20714f096756da63bdb99c5bcf57b225658b096 100644
--- a/lite/api/test_googlenet_lite.cc
+++ b/lite/api/test_googlenet_lite.cc
@@ -38,7 +38,7 @@ TEST(CXXApi, test_lite_googlenet) {
   input_tensor->Resize(input_shape);
   auto* data = input_tensor->mutable_data<float>();
   int input_num = 1;
-  for (int i = 0; i < input_shape.size(); ++i) {
+  for (size_t i = 0; i < input_shape.size(); ++i) {
     input_num *= input_shape[i];
   }
   for (int i = 0; i < input_num; i++) {
@@ -69,7 +69,7 @@ TEST(CXXApi, test_lite_googlenet) {
   for (size_t i = 0; i < results.size(); ++i) {
     EXPECT_NEAR(out->data<float>()[i * 51], results[i], 1e-5);
   }
-  ASSERT_EQ(out->shape().size(), 2);
+  ASSERT_EQ(out->shape().size(), 2u);
   ASSERT_EQ(out->shape()[0], 1);
   ASSERT_EQ(out->shape()[1], 1000);
 }
diff --git a/lite/api/test_inceptionv4_lite_x86.cc b/lite/api/test_inceptionv4_lite_x86.cc
index e986784809951390889e17f766302fc5ea459465..00f775ddb7e7bf2d2f23c34ce19e576a4d2d27ed 100644
--- a/lite/api/test_inceptionv4_lite_x86.cc
+++ b/lite/api/test_inceptionv4_lite_x86.cc
@@ -38,7 +38,7 @@ TEST(InceptionV4, test_inceptionv4_lite_x86) {
   input_tensor->Resize(input_shape);
   auto* data = input_tensor->mutable_data<float>();
   int input_num = 1;
-  for (int i = 0; i < input_shape.size(); ++i) {
+  for (size_t i = 0; i < input_shape.size(); ++i) {
     input_num *= input_shape[i];
   }
   for (int i = 0; i < input_num; i++) {
@@ -69,13 +69,13 @@ TEST(InceptionV4, test_inceptionv4_lite_x86) {
        0.0010612885,  0.00089107914, 0.0010112736,  0.00097655767}));
 
   auto out = predictor->GetOutput(0);
-  ASSERT_EQ(out->shape().size(), 2);
+  ASSERT_EQ(out->shape().size(), 2u);
   ASSERT_EQ(out->shape()[0], 1);
   ASSERT_EQ(out->shape()[1], 1000);
 
   int step = 50;
-  for (int i = 0; i < results.size(); ++i) {
-    for (int j = 0; j < results[i].size(); ++j) {
+  for (size_t i = 0; i < results.size(); ++i) {
+    for (size_t j = 0; j < results[i].size(); ++j) {
       EXPECT_NEAR(out->data<float>()[j * step + (out->shape()[1] * i)],
                   results[i][j],
                   1e-6);
diff --git a/lite/api/test_mobilenetv1_lite_x86.cc b/lite/api/test_mobilenetv1_lite_x86.cc
index 67dc1b2436988c7d0d853c945fecce27ef2d329f..8a7547b9031d0723c528e7dd6e8d7e3fb6201b7d 100644
--- a/lite/api/test_mobilenetv1_lite_x86.cc
+++ b/lite/api/test_mobilenetv1_lite_x86.cc
@@ -38,7 +38,7 @@ TEST(Mobilenet_v1, test_mobilenetv1_lite_x86) {
   input_tensor->Resize(input_shape);
   auto* data = input_tensor->mutable_data<float>();
   int input_num = 1;
-  for (int i = 0; i < input_shape.size(); ++i) {
+  for (size_t i = 0; i < input_shape.size(); ++i) {
     input_num *= input_shape[i];
   }
   for (int i = 0; i < input_num; i++) {
@@ -68,13 +68,13 @@ TEST(Mobilenet_v1, test_mobilenetv1_lite_x86) {
        0.0048292773,  0.0013995157,  0.0018453331,  0.0002428986,
        0.00020211363, 0.00013668182, 0.0005855956,  0.00025901722}));
   auto out = predictor->GetOutput(0);
-  ASSERT_EQ(out->shape().size(), 2);
+  ASSERT_EQ(out->shape().size(), 2u);
   ASSERT_EQ(out->shape()[0], 1);
   ASSERT_EQ(out->shape()[1], 1000);
 
   int step = 50;
-  for (int i = 0; i < results.size(); ++i) {
-    for (int j = 0; j < results[i].size(); ++j) {
+  for (size_t i = 0; i < results.size(); ++i) {
+    for (size_t j = 0; j < results[i].size(); ++j) {
       EXPECT_NEAR(out->data<float>()[j * step + (out->shape()[1] * i)],
                   results[i][j],
                   1e-6);
diff --git a/lite/api/test_mobilenetv2_lite_x86.cc b/lite/api/test_mobilenetv2_lite_x86.cc
index 95e88abcc8e59c6808ea2dc44cf7d1bdd53ac9d0..92c8182f7330a76bf55cf34fbb9e4fdba1fa2fc6 100644
--- a/lite/api/test_mobilenetv2_lite_x86.cc
+++ b/lite/api/test_mobilenetv2_lite_x86.cc
@@ -39,7 +39,7 @@ TEST(Mobilenet_v2, test_mobilenetv2_lite_x86) {
   input_tensor->Resize(input_shape);
   auto* data = input_tensor->mutable_data<float>();
   int input_num = 1;
-  for (int i = 0; i < input_shape.size(); ++i) {
+  for (size_t i = 0; i < input_shape.size(); ++i) {
     input_num *= input_shape[i];
   }
   for (int i = 0; i < input_num; i++) {
@@ -69,13 +69,13 @@ TEST(Mobilenet_v2, test_mobilenetv2_lite_x86) {
        0.0070957416,  0.0016094646,  0.0018807327,  0.00010506048,
        6.823785e-05,  0.00012269315, 0.0007806194,  0.00022354358}));
   auto out = predictor->GetOutput(0);
-  ASSERT_EQ(out->shape().size(), 2);
+  ASSERT_EQ(out->shape().size(), 2u);
   ASSERT_EQ(out->shape()[0], 1);
   ASSERT_EQ(out->shape()[1], 1000);
 
   int step = 50;
-  for (int i = 0; i < results.size(); ++i) {
-    for (int j = 0; j < results[i].size(); ++j) {
+  for (size_t i = 0; i < results.size(); ++i) {
+    for (size_t j = 0; j < results[i].size(); ++j) {
       EXPECT_NEAR(out->data<float>()[j * step + (out->shape()[1] * i)],
                   results[i][j],
                   1e-6);
diff --git a/lite/api/test_resnet50_lite_x86.cc b/lite/api/test_resnet50_lite_x86.cc
index 3f9b59d714de611ef0a84cfc3b283d0dddd5c294..b185159801b6264555367b41f7def1bd0e7a5a3f 100644
--- a/lite/api/test_resnet50_lite_x86.cc
+++ b/lite/api/test_resnet50_lite_x86.cc
@@ -38,7 +38,7 @@ TEST(Resnet50, test_resnet50_lite_x86) {
   input_tensor->Resize(input_shape);
   auto* data = input_tensor->mutable_data<float>();
   int input_num = 1;
-  for (int i = 0; i < input_shape.size(); ++i) {
+  for (size_t i = 0; i < input_shape.size(); ++i) {
     input_num *= input_shape[i];
   }
   for (int i = 0; i < input_num; i++) {
@@ -69,13 +69,13 @@ TEST(Resnet50, test_resnet50_lite_x86) {
        0.006387163,   0.0037145028,  0.0012812682,  0.00045948103,
        0.00013535398, 0.0002483765,  0.00076759676, 0.0002773295}));
   auto out = predictor->GetOutput(0);
-  ASSERT_EQ(out->shape().size(), 2);
+  ASSERT_EQ(out->shape().size(), 2u);
   ASSERT_EQ(out->shape()[0], 1);
   ASSERT_EQ(out->shape()[1], 1000);
 
   int step = 50;
-  for (int i = 0; i < results.size(); ++i) {
-    for (int j = 0; j < results[i].size(); ++j) {
+  for (size_t i = 0; i < results.size(); ++i) {
+    for (size_t j = 0; j < results[i].size(); ++j) {
       EXPECT_NEAR(out->data<float>()[j * step + (out->shape()[1] * i)],
                   results[i][j],
                   1e-6);
diff --git a/lite/api/transform_test.cc b/lite/api/transform_test.cc
index e1c315f4a63ffd3ed8f51fa4b73ac88b50835cab..3cd8416d5e2293642abc68e457465c8a836f790b 100644
--- a/lite/api/transform_test.cc
+++ b/lite/api/transform_test.cc
@@ -232,8 +232,8 @@ void TestModel(const std::vector<Place>& valid_places,
     for (int i = 0; i < outs->numel(); ++i) {
       LOG(INFO) << o_data[i];
     }
-    for (int i = 0; i < lod.size(); ++i) {
-      for (int j = 0; j < lod[i].size(); ++j) {
+    for (size_t i = 0; i < lod.size(); ++i) {
+      for (size_t j = 0; j < lod[i].size(); ++j) {
         LOG(INFO) << lod[i][j];
       }
     }
diff --git a/lite/backends/x86/jit/gen/matmul.cc b/lite/backends/x86/jit/gen/matmul.cc
index 010c80fac4842e74c9b8272db472ddf6cf954771..f78df73f66532f891721c74cff9c78cc3bb61922 100644
--- a/lite/backends/x86/jit/gen/matmul.cc
+++ b/lite/backends/x86/jit/gen/matmul.cc
@@ -40,7 +40,7 @@ void MatMulJitCode::genCode() {
   for (size_t g = 0; g < groups.size(); ++g) {
     size_t x_offset = 0;
     size_t wgt_offset_tmp = 0;
-    for (int i = 0; i < g; ++i) {
+    for (size_t i = 0; i < g; ++i) {
       wgt_offset_tmp += groups[i] * block_len;
     }
     for (int k = 0; k < k_; ++k) {
diff --git a/lite/backends/x86/math/beam_search.cc b/lite/backends/x86/math/beam_search.cc
index 9cf3281152840416dc141f98992499c663783b7a..5d7e98629cb89bd7a3fdee852507e0f381e54931 100644
--- a/lite/backends/x86/math/beam_search.cc
+++ b/lite/backends/x86/math/beam_search.cc
@@ -265,7 +265,7 @@ class BeamSearchFunctor<TARGET(kX86), T> {
     // size_t num_seqs = scores->NumElements(lod_level);
     size_t num_seqs = scores->lod()[lod_level].size() - 1;
     size_t seq_width = 1;
-    for (int i = 1; i < scores->dims().size(); i++) {
+    for (size_t i = 1; i < scores->dims().size(); i++) {
       seq_width *= scores->dims()[i];
     }
 
diff --git a/lite/backends/x86/math/blas.cc b/lite/backends/x86/math/blas.cc
index 2d21adaf5d22930ff720c193696eb00c8035579d..3bc5f9f67ad96e7ec699400ff6369fe48c745b7e 100644
--- a/lite/backends/x86/math/blas.cc
+++ b/lite/backends/x86/math/blas.cc
@@ -23,7 +23,7 @@ namespace math {
 MatDescriptor CreateMatrixDescriptor(const lite::DDimLite &tensor_dim,
                                      int num_flatten_cols,
                                      bool trans) {
-  PADDLE_ENFORCE_GT(tensor_dim.size(), 1);
+  PADDLE_ENFORCE_GT(tensor_dim.size(), 1u);
   MatDescriptor retv;
   if (num_flatten_cols > 1) {
     auto flatten_dim = tensor_dim.Flatten2D(num_flatten_cols);
diff --git a/lite/backends/x86/math/sequence_pooling.cc b/lite/backends/x86/math/sequence_pooling.cc
index 34c55c5714e467954bc1bb79d9b1385ef5cfe497..2d00ebad61840da5b14fbf12d9255394b2b2df1a 100644
--- a/lite/backends/x86/math/sequence_pooling.cc
+++ b/lite/backends/x86/math/sequence_pooling.cc
@@ -46,9 +46,9 @@ class MaxSeqPoolFunctor {
     auto in_dims = input.dims();
     auto out_dims = output->dims();
     auto idx_dims = index->dims();
-    PADDLE_ENFORCE_GT(in_dims.size(), 1);
-    PADDLE_ENFORCE_GT(out_dims.size(), 1);
-    for (int64_t i = 1; i < in_dims.size(); ++i) {
+    PADDLE_ENFORCE_GT(in_dims.size(), 1u);
+    PADDLE_ENFORCE_GT(out_dims.size(), 1u);
+    for (size_t i = 1; i < in_dims.size(); ++i) {
       PADDLE_ENFORCE_EQ(in_dims[i], out_dims[i]);
     }
     PADDLE_ENFORCE_EQ(idx_dims, out_dims);
@@ -95,9 +95,9 @@ class MaxSeqPoolFunctor<T, true> {
                   lite::Tensor* index) {
     auto in_dims = input.dims();
     auto out_dims = output->dims();
-    PADDLE_ENFORCE_GT(in_dims.size(), 1);
-    PADDLE_ENFORCE_GT(out_dims.size(), 1);
-    for (int64_t i = 1; i < in_dims.size(); ++i) {
+    PADDLE_ENFORCE_GT(in_dims.size(), 1u);
+    PADDLE_ENFORCE_GT(out_dims.size(), 1u);
+    for (size_t i = 1; i < in_dims.size(); ++i) {
       PADDLE_ENFORCE_EQ(in_dims[i], out_dims[i]);
     }
 
@@ -138,7 +138,7 @@ class MaxSeqPoolGradFunctor {
     auto idx_dims = index.dims();
     PADDLE_ENFORCE_GT(og_dims.size(), 1);
     PADDLE_ENFORCE_GT(ig_dims.size(), 1);
-    for (int64_t i = 1; i < og_dims.size(); ++i) {
+    for (size_t i = 1; i < og_dims.size(); ++i) {
       PADDLE_ENFORCE_EQ(og_dims[i], ig_dims[i]);
     }
     PADDLE_ENFORCE_EQ(idx_dims, og_dims);
diff --git a/lite/core/arena/framework.cc b/lite/core/arena/framework.cc
index 614ee990a9811ab74ceedb4fa000fa385698d679..731215f542567ec3ff0cc87d6990624bfa6b2bc2 100644
--- a/lite/core/arena/framework.cc
+++ b/lite/core/arena/framework.cc
@@ -107,7 +107,7 @@ void TestCase::PrepareInputsForInstruction() {
           CHECK(!shared_tensor_array->empty())
               << "shared_tensor_array is empty yet";
           target_tensor_array->resize(shared_tensor_array->size());
-          for (int i = 0; i < shared_tensor_array->size(); i++) {
+          for (size_t i = 0; i < shared_tensor_array->size(); i++) {
             target_tensor_array->at(i).Resize(
                 shared_tensor_array->at(i).dims());
             TargetCopy(param_type->type->target(),
@@ -219,7 +219,7 @@ bool TestCase::CheckPrecision(const std::string& var_name,
     auto b_tensor_array =
         base_scope_->FindVar(var_name)->GetMutable<std::vector<Tensor>>();
     CHECK_EQ(a_tensor_array->size(), b_tensor_array->size());
-    for (int i = 0; i < a_tensor_array->size(); i++) {
+    for (size_t i = 0; i < a_tensor_array->size(); i++) {
       Tensor* a_tensor = &(a_tensor_array->at(i));
       Tensor* b_tensor = &(b_tensor_array->at(i));
       if (a_tensor->dims().size() == 0 && b_tensor->dims().size() == 0) {
diff --git a/lite/core/arena/framework.h b/lite/core/arena/framework.h
index 7050355fbfae55b9ba626119cd95f8e952c27430..20a0792155f0b4ea8faa7c3fc15ea5c4767352ac 100644
--- a/lite/core/arena/framework.h
+++ b/lite/core/arena/framework.h
@@ -166,7 +166,7 @@ class TestCase {
   // TODO(Superjomn) Move this method to utils or DDim?
   bool ShapeEquals(const DDim& a, const DDim& b) {
     if (a.size() != b.size()) return false;
-    for (int i = 0; i < a.size(); i++) {
+    for (size_t i = 0; i < a.size(); i++) {
       if (a[i] != b[i]) return false;
     }
     return true;
diff --git a/lite/core/device_info.cc b/lite/core/device_info.cc
index 29ac96ed744b016833a746b35002dd68109efd8b..09da06a4168268c670577c159a2a306a8959d81d 100644
--- a/lite/core/device_info.cc
+++ b/lite/core/device_info.cc
@@ -947,7 +947,7 @@ void DeviceInfo::RequestPowerNoBindMode(int thread_num) {
     active_ids_ = core_ids_;
   } else {
     active_ids_.resize(thread_num);
-    for (int i = 0; i < thread_num; ++i) {
+    for (uint32_t i = 0; i < thread_num; ++i) {
       if (i < big_core_ids_.size()) {
         active_ids_[i] = big_core_ids_[i];
       } else {
diff --git a/lite/core/kernel.cc b/lite/core/kernel.cc
index 7ec718cb3881c10dec08376419b419777c71bba6..194d736a4c0cf6fa18eae119589c5fa1fd08bca0 100644
--- a/lite/core/kernel.cc
+++ b/lite/core/kernel.cc
@@ -57,7 +57,7 @@ void KernelBase::ParseKernelType(const std::string &kernel_type,
                                  std::string *alias,
                                  Place *place) {
   auto parts = Split(kernel_type, "/");
-  CHECK_EQ(parts.size(), 5);
+  CHECK_EQ(parts.size(), 5u);
   *op_type = parts[0];
   *alias = parts[1];
 
diff --git a/lite/core/mir/fusion/conv_bn_fuser.cc b/lite/core/mir/fusion/conv_bn_fuser.cc
index 43869beddd0af701d5f78ea047b30f6b136e6b3f..143a7cecce8c1c45ada9ad31e8e4bea5447fec68 100644
--- a/lite/core/mir/fusion/conv_bn_fuser.cc
+++ b/lite/core/mir/fusion/conv_bn_fuser.cc
@@ -163,23 +163,23 @@ void ConvBNFuser::InsertNewNode(SSAGraph* graph, const key2nodes_t& matched) {
       int c_size = conv_weight_t->dims()[1] * conv_weight_t->dims()[2] *
                    conv_weight_t->dims()[3];
       int hw = conv_weight_t->dims()[2] * conv_weight_t->dims()[3];
-      for (unsigned int k = 0; k < conv_weight_t->dims()[0]; ++k) {
-        for (unsigned int i = 0; i < h; ++i) {
+      for (int k = 0; k < conv_weight_t->dims()[0]; ++k) {
+        for (int i = 0; i < h; ++i) {
           weight_scale[i] *= fabsf(alpha_data[i]);
           if (alpha_data[i] < 0.f) {
             auto ptr_row = conv_weight_d + k * c_size + i * hw;
-            for (unsigned int j = 0; j < hw; ++j) {
+            for (int j = 0; j < hw; ++j) {
               ptr_row[j] *= -1;
             }
           }
         }
       }
     } else {
-      for (unsigned int i = 0; i < h; ++i) {
+      for (int i = 0; i < h; ++i) {
         weight_scale[i] *= fabsf(alpha_data[i]);
         if (alpha_data[i] < 0.f) {
           auto ptr_row = conv_weight_d + i * w;
-          for (unsigned int j = 0; j < w; ++j) {
+          for (int j = 0; j < w; ++j) {
             ptr_row[j] *= -1;
           }
         }
@@ -203,17 +203,17 @@ void ConvBNFuser::InsertNewNode(SSAGraph* graph, const key2nodes_t& matched) {
       int c_size = conv_weight_t->dims()[1] * conv_weight_t->dims()[2] *
                    conv_weight_t->dims()[3];
       int hw = conv_weight_t->dims()[2] * conv_weight_t->dims()[3];
-      for (unsigned int k = 0; k < conv_weight_t->dims()[0]; ++k) {
-        for (unsigned int i = 0; i < h; ++i) {
+      for (int k = 0; k < conv_weight_t->dims()[0]; ++k) {
+        for (int i = 0; i < h; ++i) {
           auto ptr_row = conv_weight_d + k * c_size + i * hw;
-          for (unsigned int j = 0; j < hw; ++j) {
+          for (int j = 0; j < hw; ++j) {
             ptr_row[j] *= alpha_data[i];
           }
         }
       }
     } else {
-      for (unsigned int i = 0; i < h; ++i) {    // n: conv2d output channels
-        for (unsigned int j = 0; j < w; ++j) {  // w: conv2d input channels
+      for (int i = 0; i < h; ++i) {    // n: conv2d output channels
+        for (int j = 0; j < w; ++j) {  // w: conv2d input channels
           conv_weight_d[i * w + j] *= alpha_data[i];
         }
       }
diff --git a/lite/core/mir/fusion/quant_dequant_op_fuser.cc b/lite/core/mir/fusion/quant_dequant_op_fuser.cc
index a3a98b871fb4b6f8230299cda978b0f1f8faa779..2c7cc2fe5547d6004ded99f28698478cec0a3639 100644
--- a/lite/core/mir/fusion/quant_dequant_op_fuser.cc
+++ b/lite/core/mir/fusion/quant_dequant_op_fuser.cc
@@ -260,7 +260,7 @@ void ChannelWiseDequantOpFuser::InsertNewNode(SSAGraph* graph,
   auto channel_scale_tensor =
       scope->FindVar(channel_scale_name)->GetMutable<lite::Tensor>();
   auto* channel_scale_data = channel_scale_tensor->data<float>();
-  for (int i = 0; i < channel_scale_tensor->data_size(); i++) {
+  for (size_t i = 0; i < channel_scale_tensor->data_size(); i++) {
     weight_scale.push_back(channel_scale_data[i] / range);
   }
 
diff --git a/lite/core/mir/mlu_postprocess_pass.cc b/lite/core/mir/mlu_postprocess_pass.cc
index 15f62f36b0f026dc42ecbb274c946e294c7fc44e..ba48d5d4ead5ea922ded0bff3a87c2c127595790 100644
--- a/lite/core/mir/mlu_postprocess_pass.cc
+++ b/lite/core/mir/mlu_postprocess_pass.cc
@@ -292,7 +292,7 @@ void MLUPostprocessPass::GetSubgraphOpArgType(Node* inst_node,
 
   // get subgraph op's type info
   size_t kernel_size = inst_node->AsStmt().kernels().size();
-  CHECK_GT(kernel_size, 0);
+  CHECK_GT(kernel_size, 0u);
   VLOG(4) << "subgraph kernel size: " << kernel_size;
 
   for (size_t i = 0; i < kernel_size; ++i) {
@@ -450,7 +450,7 @@ bool MLUPostprocessPass::IsFirstConvInSubgraph(Node* arg_node, Node* inst) {
   auto* block_desc =
       static_cast<operators::SubgraphOp*>(inst->AsStmt().op().get())
           ->GetSubBlock();
-  for (int op_idx = 0; op_idx < block_desc->OpsSize(); op_idx++) {
+  for (size_t op_idx = 0; op_idx < block_desc->OpsSize(); op_idx++) {
     auto op_desc = block_desc->GetOp<cpp::OpDesc>(op_idx);
     CHECK(op_desc);
     if (op_desc->Type() == "conv2d") {
diff --git a/lite/core/mir/subgraph/subgraph_detector.cc b/lite/core/mir/subgraph/subgraph_detector.cc
index b61f7f365f51a32e267dd12943be5fcfadb3e08a..6bab454c42a68a7513aa01ff06cc2be6c970e199 100644
--- a/lite/core/mir/subgraph/subgraph_detector.cc
+++ b/lite/core/mir/subgraph/subgraph_detector.cc
@@ -47,8 +47,8 @@ std::string SubgraphVisualizer::operator()() {
       "turquoise4",   "snow3",          "sienna4",        "salmon2",
   };
   std::unordered_map<Node *, int> subgraph_indices;
-  for (int i = 0; i < subgraphs_.size(); i++) {
-    for (int j = 0; j < subgraphs_[i].size(); j++) {
+  for (size_t i = 0; i < subgraphs_.size(); i++) {
+    for (size_t j = 0; j < subgraphs_[i].size(); j++) {
       subgraph_indices[subgraphs_[i][j]] = i;
     }
   }
@@ -538,7 +538,8 @@ void SubgraphFuser::ReplaceNodesWithSubgraphs(SSAGraph *graph,
   std::vector<std::vector<Node *>> subgraphs =
       SubgraphDetector(graph, teller)();
   SubgraphVisualizer(graph, subgraphs)();
-  for (int subgraph_idx = 0; subgraph_idx < subgraphs.size(); subgraph_idx++) {
+  for (size_t subgraph_idx = 0; subgraph_idx < subgraphs.size();
+       subgraph_idx++) {
     if (subgraphs[subgraph_idx].size() >= min_subgraph_size) {
       InsertNewNode(graph, subgraph_idx, subgraphs[subgraph_idx]);
     }
diff --git a/lite/core/mir/subgraph/subgraph_detector_test.cc b/lite/core/mir/subgraph/subgraph_detector_test.cc
index 1e54e1497b5d49754a705340aafa30ded1c2a727..f52c0332fa3cfce904d2b7c8bf010bc3d3ac6ac9 100644
--- a/lite/core/mir/subgraph/subgraph_detector_test.cc
+++ b/lite/core/mir/subgraph/subgraph_detector_test.cc
@@ -36,8 +36,8 @@ std::vector<std::string> AddFCDesc(
     const std::shared_ptr<Scope>& scope,
     const std::vector<std::string>& input_var_names,
     const std::vector<int64_t>& wshape) {
-  CHECK_EQ(input_var_names.size(), 1);
-  CHECK_EQ(wshape.size(), 2);
+  CHECK_EQ(input_var_names.size(), 1u);
+  CHECK_EQ(wshape.size(), 2u);
   static int id = 0;
   std::string prefix = "fc_" + paddle::lite::to_string(id);
   auto* op_desc = block_desc->AddOp<cpp::OpDesc>();
@@ -169,8 +169,8 @@ TEST(Subgraph, detect_simple_model) {
   };
   std::vector<std::vector<mir::Node*>> subgraphs =
       mir::SubgraphDetector(graph.get(), teller)();
-  ASSERT_EQ(subgraphs.size(), 1);
-  ASSERT_EQ(graph->nodes().size(), 9);
+  ASSERT_EQ(subgraphs.size(), 1u);
+  ASSERT_EQ(graph->nodes().size(), 9u);
   mir::SubgraphVisualizer(graph.get(), subgraphs)();
 }
 
@@ -221,7 +221,7 @@ TEST(Subgraph, detect_custom_model) {
   std::vector<std::vector<mir::Node*>> subgraphs =
       mir::SubgraphDetector(graph.get(), teller)();
   mir::SubgraphVisualizer(graph.get(), subgraphs)();
-  ASSERT_EQ(subgraphs.size(), 1);
+  ASSERT_EQ(subgraphs.size(), 1u);
 }
 
 }  // namespace lite
diff --git a/lite/core/mir/subgraph/subgraph_pass_test.cc b/lite/core/mir/subgraph/subgraph_pass_test.cc
index a2369adc5d882310503cbf52fa5394098d824b40..c638793c08160eb8ee7edabeab0977541e85d82a 100644
--- a/lite/core/mir/subgraph/subgraph_pass_test.cc
+++ b/lite/core/mir/subgraph/subgraph_pass_test.cc
@@ -39,7 +39,7 @@ std::vector<std::vector<int64_t>> ShapeParsing(std::string text) {
   std::vector<std::vector<int64_t>> shapes;
   std::vector<std::string> shape_strings = Split(text, ":");
   shapes.resize(shape_strings.size());
-  for (int i = 0; i < shape_strings.size(); i++) {
+  for (size_t i = 0; i < shape_strings.size(); i++) {
     std::vector<std::string> shape_nums = Split(shape_strings[i], ",");
     for (auto shape_num : shape_nums) {
       shapes[i].push_back(atoi(shape_num.c_str()));
@@ -66,7 +66,7 @@ void FillInputTensors(
   for (int j = 0; j < input_tensor_size; j++) {                \
     input_tensor_data[j] = static_cast<type>(value);           \
   }
-  for (int i = 0; i < input_tensor_shape.size(); i++) {
+  for (size_t i = 0; i < input_tensor_shape.size(); i++) {
     auto input_tensor = predictor->GetInput(i);
     input_tensor->Resize(input_tensor_shape[i]);
     auto input_tensor_size = ShapeProduction(input_tensor->shape());
@@ -95,7 +95,7 @@ void CheckOutputTensors(
             << " abs_diff: " << abs_diff << " rel_diff: " << rel_diff;        \
     EXPECT_LT(rel_diff, 0.1);                                                 \
   }
-  for (int i = 0; i < output_tensor_type.size(); i++) {
+  for (size_t i = 0; i < output_tensor_type.size(); i++) {
     auto tar_output_tensor = tar_predictor->GetOutput(i);
     auto ref_output_tensor = ref_predictor->GetOutput(i);
     auto tar_output_tensor_size = ShapeProduction(tar_output_tensor->shape());
diff --git a/lite/core/op_lite.cc b/lite/core/op_lite.cc
index f8a706179374a0c86e28cf9a3638f5df2c932540..941a9e9f88cf04ef47487237b1a3f6509dea762b 100644
--- a/lite/core/op_lite.cc
+++ b/lite/core/op_lite.cc
@@ -41,7 +41,7 @@ bool OpLite::InferShapeWithCache() {
        iter++) {
     // combined dims value into new_hash value.
     auto &element_dims = (*iter)->dims();
-    for (int i = 0; i < element_dims.size(); i++) {
+    for (size_t i = 0; i < element_dims.size(); i++) {
       new_hash =
           lite::hash_combine(new_hash, static_cast<int>(element_dims[i]));
     }
@@ -49,7 +49,7 @@ bool OpLite::InferShapeWithCache() {
     auto &emement_lods = (*iter)->lod();
     for (auto lod_iter = emement_lods.begin(); lod_iter != emement_lods.end();
          lod_iter++) {
-      for (int i = 0; i < lod_iter->size(); i++) {
+      for (size_t i = 0; i < lod_iter->size(); i++) {
         new_hash =
             lite::hash_combine(new_hash, static_cast<int>(lod_iter->at(i)));
       }
@@ -60,7 +60,7 @@ bool OpLite::InferShapeWithCache() {
     // if current hash value is consistent with io_shape_lod_hash_,
     // previous outputs shape and lod are reused.
     auto *current_outputs = param_.output_tensor_ptrs();
-    for (int i = 0; i < current_outputs->size(); i++) {
+    for (size_t i = 0; i < current_outputs->size(); i++) {
       current_outputs->at(i)->Resize(last_output_shapes[i]);
       current_outputs->at(i)->set_lod(last_output_lods[i]);
     }
@@ -69,7 +69,7 @@ bool OpLite::InferShapeWithCache() {
     io_shape_lod_hash_ = new_hash;
     this->InferShapeImpl();
     auto *current_outputs = param_.output_tensor_ptrs();
-    for (int i = 0; i < current_outputs->size(); i++) {
+    for (size_t i = 0; i < current_outputs->size(); i++) {
       last_output_shapes[i] = current_outputs->at(i)->dims();
       last_output_lods[i] = current_outputs->at(i)->lod();
     }
diff --git a/lite/core/program.cc b/lite/core/program.cc
index 1193e3c84f66b9d1dfb39d5dcc74265d212ab7ab..5ddf6c0e935a851cc0b3c3eb7554609939ef1cbf 100644
--- a/lite/core/program.cc
+++ b/lite/core/program.cc
@@ -72,7 +72,7 @@ void RuntimeProgram::UpdateVarsOfProgram(cpp::ProgramDesc* desc) {
   std::unordered_map<std::string, cpp::VarDesc> origin_var_maps;
   auto& main_block = *desc->GetBlock<cpp::BlockDesc>(0);
   auto var_size = main_block.VarsSize();
-  for (int i = 0; i < var_size; i++) {
+  for (size_t i = 0; i < var_size; i++) {
     auto v = main_block.GetVar<cpp::VarDesc>(i);
     auto name = v->Name();
     origin_var_maps.emplace(name, *v);
diff --git a/lite/core/tensor.cc b/lite/core/tensor.cc
index ecb9935dfd13c09cbd1a20f3833e6ab76161192a..1ae291dd40d19940e93bfda9b0c22f4092ce7988 100644
--- a/lite/core/tensor.cc
+++ b/lite/core/tensor.cc
@@ -100,7 +100,7 @@ void *TensorLite::mutable_data(TargetType target, size_t memory_size) {
 
 void TensorLite::ResetBuffer(std::shared_ptr<Buffer> buffer,
                              size_t memory_size) {
-  CHECK_EQ(offset_, 0)
+  CHECK_EQ(offset_, 0u)
       << "Only the offset is supported to zero when the Buffer is reset.";
   if (buffer_) {
     CHECK_LE(memory_size_, buffer->space())
diff --git a/lite/kernels/mlu/bridges/act_op_test.cc b/lite/kernels/mlu/bridges/act_op_test.cc
index 7cec0529e49e694c362b3e0a550948f7855c85a2..2b7747f4d8b647b8cb621876907f6178ebf9fe88 100644
--- a/lite/kernels/mlu/bridges/act_op_test.cc
+++ b/lite/kernels/mlu/bridges/act_op_test.cc
@@ -44,40 +44,40 @@ void act_ref(const std::shared_ptr<operators::ActivationOp> op) {
 
   // "sigmoid","relu","tanh","relu_clipped","leaky_relu","softsign","hard_sigmoid"
   if (op_type == "sigmoid") {
-    for (size_t i = 0; i < out->numel(); i++) {
+    for (int i = 0; i < out->numel(); i++) {
       out_data[i] = 1.f / (1.f + std::exp(-x_data[i]));
     }
   } else if (op_type == "relu") {
-    for (size_t i = 0; i < out->numel(); i++) {
+    for (int i = 0; i < out->numel(); i++) {
       out_data[i] = std::max(0.f, x_data[i]);
     }
   } else if (op_type == "tanh") {
-    for (size_t i = 0; i < out->numel(); i++) {
+    for (int i = 0; i < out->numel(); i++) {
       out_data[i] = (std::exp(x_data[i]) - std::exp(-x_data[i])) /
                     (std::exp(x_data[i]) + std::exp(-x_data[i]));
     }
   } else if (op_type == "relu_clipped") {
     auto relu_clipped_coef = op_info->GetAttr<float>("Relu_clipped_coef");
-    for (size_t i = 0; i < out->numel(); i++) {
+    for (int i = 0; i < out->numel(); i++) {
       out_data[i] = std::min(std::max(0.f, x_data[i]), relu_clipped_coef);
     }
   } else if (op_type == "relu6") {
-    for (size_t i = 0; i < out->numel(); i++) {
+    for (int i = 0; i < out->numel(); i++) {
       out_data[i] = std::min(std::max(0.f, x_data[i]), 6.f);
     }
   } else if (op_type == "leaky_relu") {
     auto alpha = op_info->GetAttr<float>("alpha");
-    for (size_t i = 0; i < out->numel(); i++) {
+    for (int i = 0; i < out->numel(); i++) {
       out_data[i] = std::max(x_data[i], x_data[i] * alpha);
     }
   } else if (op_type == "softsign") {
-    for (size_t i = 0; i < out->numel(); i++) {
+    for (int i = 0; i < out->numel(); i++) {
       out_data[i] = x_data[i] / (1 + std::abs(x_data[i]));
     }
   } else if (op_type == "hard_sigmoid") {
     auto slope = op_info->GetAttr<float>("slope");
     auto offset = op_info->GetAttr<float>("offset");
-    for (size_t i = 0; i < out->numel(); i++) {
+    for (int i = 0; i < out->numel(); i++) {
       out_data[i] = std::min(1.f, slope * x_data[i] + offset);
       out_data[i] = std::max(0.f, out_data[i]);
     }
diff --git a/lite/kernels/mlu/bridges/concat_op_test.cc b/lite/kernels/mlu/bridges/concat_op_test.cc
index c4b48a9ef45430ec5867d231bbc2d0a798ec66d0..1dbcaf7160fd36ab75c4a1139555650b98030482 100644
--- a/lite/kernels/mlu/bridges/concat_op_test.cc
+++ b/lite/kernels/mlu/bridges/concat_op_test.cc
@@ -37,7 +37,7 @@ void concat_ref(const std::shared_ptr<operators::ConcatOpLite> op) {
       scope->FindVar(op_info->Output("Out").front())->GetMutable<Tensor>();
   int axis = op_info->GetAttr<int>("axis");
   std::vector<lite::Tensor*> inputs_concat(inputs.size());
-  for (int j = 0; j < inputs.size(); ++j) {
+  for (size_t j = 0; j < inputs.size(); ++j) {
     inputs_concat[j] = inputs[j];
   }
   size_t num = inputs.size();
@@ -48,7 +48,7 @@ void concat_ref(const std::shared_ptr<operators::ConcatOpLite> op) {
   }
   int out_rows = rows, out_cols = 0;
   std::vector<int64_t> inputs_cols(inputs.size());
-  for (int i = 0; i < num; ++i) {
+  for (size_t i = 0; i < num; ++i) {
     int t_cols = inputs[i]->numel() / rows;
     out_cols += t_cols;
     inputs_cols[i] = t_cols;
@@ -56,7 +56,7 @@ void concat_ref(const std::shared_ptr<operators::ConcatOpLite> op) {
   for (int k = 0; k < out_rows; ++k) {
     float* dst_ptr = out->mutable_data<float>() + k * out_cols;
     int col_idx = 0;
-    for (int j = 0; j < num; ++j) {
+    for (size_t j = 0; j < num; ++j) {
       int col_len = inputs_cols[j];
       const float* src_prt = inputs[j]->data<float>() + k * col_len;
       std::memcpy(dst_ptr + col_idx, src_prt, sizeof(float) * col_len);
diff --git a/lite/kernels/mlu/bridges/conv_op.cc b/lite/kernels/mlu/bridges/conv_op.cc
index 6a7ef408eb7432950d5a0985dd6e174236e937e0..e7e21f7ad2f64275746e015289c9372368e46f5c 100644
--- a/lite/kernels/mlu/bridges/conv_op.cc
+++ b/lite/kernels/mlu/bridges/conv_op.cc
@@ -43,20 +43,20 @@ int ConvConverter(void* ctx, OpLite* op, KernelBase* kernel) {
   const auto output_shape = output->dims().Vectorize();
   const auto bs = input_dims[0];
   const auto oc = filter_dims[0];
-  CHECK_EQ(input_dims.size(), 4);
-  CHECK_EQ(filter_dims.size(), 4);
+  CHECK_EQ(input_dims.size(), 4u);
+  CHECK_EQ(filter_dims.size(), 4u);
   const auto strides = op_info->GetAttr<std::vector<int>>("strides");
   auto dilations = op_info->GetAttr<std::vector<int>>("dilations");
   auto paddings = op_info->GetAttr<std::vector<int>>("paddings");
-  CHECK_EQ(strides.size(), 2L);
-  CHECK_EQ(dilations.size(), 2L);
-  if (paddings.size() == 2L) {
+  CHECK_EQ(strides.size(), 2u);
+  CHECK_EQ(dilations.size(), 2u);
+  if (paddings.size() == 2u) {
     for (size_t i = 0; i < strides.size(); ++i) {
       int copy_pad = *(paddings.begin() + 2 * i);
       paddings.insert(paddings.begin() + 2 * i + 1, copy_pad);
     }
   }
-  CHECK_EQ(paddings.size(), 4L)
+  CHECK_EQ(paddings.size(), 4u)
       << "Paddings size should be the same or twice as the input size.";
 
   const std::string padding_algorithm =
diff --git a/lite/kernels/mlu/bridges/conv_op_test.cc b/lite/kernels/mlu/bridges/conv_op_test.cc
index e34dd7c2a85dbda62596b6e82d820fc437bfd194..1b04814d7d88d227d0bb3e0b58aef26d62f06966 100644
--- a/lite/kernels/mlu/bridges/conv_op_test.cc
+++ b/lite/kernels/mlu/bridges/conv_op_test.cc
@@ -173,10 +173,10 @@ void test_conv(int bs,
   Tensor input_int;
   input_int.Resize(input_shape);
   FillTensor<int8_t, int8_t>(&input_int, -127, 127);
-  for (int i = 0; i < input->data_size(); i++) {
+  for (size_t i = 0; i < input->data_size(); i++) {
     input->mutable_data<float>()[i] = input_int.data<int8_t>()[i] * input_scale;
   }
-  for (int i = 0; i < filter->data_size(); i++) {
+  for (size_t i = 0; i < filter->data_size(); i++) {
     filter->mutable_data<float>()[i] =
         filter_int->data<int8_t>()[i] * filter_scale;
   }
diff --git a/lite/kernels/mlu/bridges/fc_op_test.cc b/lite/kernels/mlu/bridges/fc_op_test.cc
index 8f92b6abad97650100d0862d49550abaf62daac9..fe1c889f431350b4175ac400aefe77e6392405c5 100644
--- a/lite/kernels/mlu/bridges/fc_op_test.cc
+++ b/lite/kernels/mlu/bridges/fc_op_test.cc
@@ -97,11 +97,11 @@ void test_fc(const std::vector<int64_t>& input_shape,
   Tensor input_int;
   input_int.Resize(input_shape);
   FillTensor<int8_t, int8_t>(&input_int, -127, 127);
-  for (int i = 0; i < input->data_size(); i++) {
+  for (size_t i = 0; i < input->data_size(); i++) {
     input->mutable_data<float>()[i] = input_int.data<int8_t>()[i] * input_scale;
   }
 
-  for (int i = 0; i < w->data_size(); i++) {
+  for (size_t i = 0; i < w->data_size(); i++) {
     w->mutable_data<float>()[i] = w_int->data<int8_t>()[i] * w_scale;
   }
 
diff --git a/lite/kernels/mlu/bridges/interpolate_op.cc b/lite/kernels/mlu/bridges/interpolate_op.cc
index e201199824d8042abd6002ccbe5bb659a9ca2898..2c1a2aeeff799d31d4328169fce058259543fb1f 100644
--- a/lite/kernels/mlu/bridges/interpolate_op.cc
+++ b/lite/kernels/mlu/bridges/interpolate_op.cc
@@ -36,7 +36,7 @@ int InterpolateConverter(void* ctx, OpLite* op, KernelBase* kernel) {
   auto x = scope->FindVar(x_var_name)->GetMutable<Tensor>();
   auto out = scope->FindVar(out_var_name)->GetMutable<Tensor>();
   auto x_dims = x->dims();
-  CHECK_EQ(x_dims.size(), 4);
+  CHECK_EQ(x_dims.size(), 4u);
   auto scale = op_info->GetAttr<float>("scale");
   auto out_w = op_info->GetAttr<int>("out_w");
   auto out_h = op_info->GetAttr<int>("out_h");
diff --git a/lite/kernels/mlu/bridges/interpolate_op_test.cc b/lite/kernels/mlu/bridges/interpolate_op_test.cc
index 0e99da64358e6590af0b8e57dc3ddec142c8d0f0..13f5bfb31bc2856c2da467e8511cd5d2c973492d 100644
--- a/lite/kernels/mlu/bridges/interpolate_op_test.cc
+++ b/lite/kernels/mlu/bridges/interpolate_op_test.cc
@@ -85,7 +85,7 @@ void BilinearInterpRef(const lite::Tensor* x,
   int channel_size = x_dims[1];
   auto x_h = x_dims[2];
   auto x_w = x_dims[3];
-  CHECK_EQ(x_dims.size(), 4);
+  CHECK_EQ(x_dims.size(), 4u);
 
   auto out_dims = out->dims();
   int out_h = out_dims[2];
diff --git a/lite/kernels/mlu/bridges/utility.cc b/lite/kernels/mlu/bridges/utility.cc
index f18a46518c09a69803a069ce40c1d7e3c01e9eca..cd78553a652433fc41334a6bff5575031f5125e0 100644
--- a/lite/kernels/mlu/bridges/utility.cc
+++ b/lite/kernels/mlu/bridges/utility.cc
@@ -59,10 +59,10 @@ void dequant(float* dst,
              size_t size,
              size_t size_in,
              std::vector<float> scales) {
-  for (int out = 0; out < size_o; ++out) {
-    for (int s = 0; s < size; ++s) {
+  for (size_t out = 0; out < size_o; ++out) {
+    for (size_t s = 0; s < size; ++s) {
       auto scale = scales[s];
-      for (int in = 0; in < size_in; ++in) {
+      for (size_t in = 0; in < size_in; ++in) {
         int idx = in + s * size_in + out * size_in * size;
         dst[idx] = static_cast<float>(src[idx]) * scale;
       }
diff --git a/lite/kernels/npu/bridges/engine.cc b/lite/kernels/npu/bridges/engine.cc
index 9961d5f17e285350414f1c8ae72fe19d760312de..6e639a37badf45e4a01f542011f0149e93e06772 100644
--- a/lite/kernels/npu/bridges/engine.cc
+++ b/lite/kernels/npu/bridges/engine.cc
@@ -30,7 +30,7 @@ int Engine::BuildOriginProgram() {
   // TODO(hong19860320) The block_desc need to be divided into subgraphs during
   // the exection time. But only see them as a subgraph now.
   origin_program_.clear();
-  for (int op_idx = 0; op_idx < block_desc_->OpsSize(); op_idx++) {
+  for (size_t op_idx = 0; op_idx < block_desc_->OpsSize(); op_idx++) {
     auto op_desc = block_desc_->GetOp<cpp::OpDesc>(op_idx);
     CHECK(op_desc);
     std::string op_type = op_desc->Type();
@@ -46,7 +46,7 @@ int Engine::BuildOriginProgram() {
       VLOG(3) << "Found the attr '" << kKernelTypeAttr << "': " << kernel_type
               << " for " << op_type;
       auto kernels = op->CreateKernels({place});
-      CHECK_GT(kernels.size(), 0) << "No kernels found for " << op_type;
+      CHECK_GT(kernels.size(), 0u) << "No kernels found for " << op_type;
       auto it = std::find_if(
           kernels.begin(), kernels.end(), [&](std::unique_ptr<KernelBase>& it) {
             return it->alias() == alias;
@@ -96,7 +96,7 @@ int Engine::Build() {
 }
 
 bool Engine::InputShapeChanged() {
-  for (int i = 0; i < origin_itensors_.size(); i++) {
+  for (size_t i = 0; i < origin_itensors_.size(); i++) {
     if (origin_itensors_[i]->dims() != origin_idims_[i]) {
       return true;
     }
diff --git a/lite/kernels/x86/elementwise_op_function.h b/lite/kernels/x86/elementwise_op_function.h
index 42ea38d979e39f97a8aef971370c83303c53c48f..c49f21d1a8ee20db249274874e21accd00dfbcd1 100644
--- a/lite/kernels/x86/elementwise_op_function.h
+++ b/lite/kernels/x86/elementwise_op_function.h
@@ -64,14 +64,14 @@ inline void get_mid_dims(const lite::DDim &x_dims,
     for (int i = 0; i < axis; ++i) {
       (*pre) *= x_dims[i];
     }
-    for (int i = 0; i < y_dims.size(); ++i) {
+    for (size_t i = 0; i < y_dims.size(); ++i) {
       if (x_dims[i + axis] != y_dims[i]) {
         // only support single y_dims[i] = 1 now.
         PADDLE_ENFORCE_EQ(
             *mid_flag, 0, "Broadcast support y_dims with single 1.");
         PADDLE_ENFORCE_EQ(y_dims[i], 1, "Broadcast dimension mismatch.");
         // m*n*k m*1*k
-        for (int j = 0; j < i; ++j) {
+        for (size_t j = 0; j < i; ++j) {
           (*pre) *= y_dims[j];
         }
         *n = std::max(x_dims[i + axis], y_dims[i]);
@@ -82,11 +82,11 @@ inline void get_mid_dims(const lite::DDim &x_dims,
       (*n) *= y_dims[i];
     }
     if (*mid_flag) {
-      for (int i = mid + 1; i < x_dims.size(); ++i) {
+      for (size_t i = mid + 1; i < x_dims.size(); ++i) {
         (*post) *= x_dims[i];
       }
     } else {
-      for (int i = axis + y_dims.size(); i < x_dims.size(); ++i) {
+      for (size_t i = axis + y_dims.size(); i < x_dims.size(); ++i) {
         (*post) *= x_dims[i];
       }
     }
@@ -95,13 +95,13 @@ inline void get_mid_dims(const lite::DDim &x_dims,
       (*pre) *= x_dims[i];
     }
 
-    for (int i = 0; i < y_dims.size(); ++i) {
+    for (size_t i = 0; i < y_dims.size(); ++i) {
       PADDLE_ENFORCE_EQ(
           x_dims[i + axis], y_dims[i], "Broadcast dimension mismatch.");
       (*n) *= y_dims[i];
     }
 
-    for (int i = axis + y_dims.size(); i < x_dims.size(); ++i) {
+    for (size_t i = axis + y_dims.size(); i < x_dims.size(); ++i) {
       (*post) *= x_dims[i];
     }
   }
@@ -116,7 +116,7 @@ inline lite::DDim trim_trailing_singular_dims(const lite::DDim &dims) {
 
   std::vector<int64_t> trim_dims;
   trim_dims.resize(actual_dims_size);
-  for (int i = 0; i < actual_dims_size; ++i) {
+  for (size_t i = 0; i < actual_dims_size; ++i) {
     trim_dims[i] = dims[i];
   }
   if (trim_dims.size() == 0) {
diff --git a/lite/kernels/x86/fill_constant_batch_size_like_compute_test.cc b/lite/kernels/x86/fill_constant_batch_size_like_compute_test.cc
index e324b599836059ca3560593950f689eabd393ea0..16bec18a1c1c4d0075e1ed1dcc4f3a3462917868 100644
--- a/lite/kernels/x86/fill_constant_batch_size_like_compute_test.cc
+++ b/lite/kernels/x86/fill_constant_batch_size_like_compute_test.cc
@@ -71,7 +71,7 @@ TEST(fill_constant_batch_size_like_x86, run_test) {
 
   std::vector<float> ref_results{
       3.5, 3.5, 3.5, 3.5, 3.5, 3.5, 3.5, 3.5, 3.5, 3.5};
-  for (int i = 0; i < ref_results.size(); i++) {
+  for (size_t i = 0; i < ref_results.size(); i++) {
     EXPECT_NEAR(out_data[i], ref_results[i], 1e-3);
   }
 }
diff --git a/lite/kernels/x86/gather_compute.h b/lite/kernels/x86/gather_compute.h
index bd01d9da3af1640770838c262dcd848b557d40c3..e63332e87a079e234a0fc72ee2756afd2ebdd94c 100644
--- a/lite/kernels/x86/gather_compute.h
+++ b/lite/kernels/x86/gather_compute.h
@@ -56,7 +56,7 @@ void CPUGather(const lite::Tensor* src,
 
   // slice size
   int slice_size = 1;
-  for (int i = 1; i < src_dims.size(); ++i) slice_size *= src_dims[i];
+  for (size_t i = 1; i < src_dims.size(); ++i) slice_size *= src_dims[i];
 
   const size_t slice_bytes = slice_size * sizeof(T);
   for (int64_t i = 0; i < index_size; ++i) {
diff --git a/lite/kernels/x86/layer_norm_compute_test.cc b/lite/kernels/x86/layer_norm_compute_test.cc
index a5244bcc6f2c561b5eac2fc74b1cc8c5f12417d6..d39500a5e8827230ddeecd6bbe30f8c0a47ee929 100644
--- a/lite/kernels/x86/layer_norm_compute_test.cc
+++ b/lite/kernels/x86/layer_norm_compute_test.cc
@@ -108,7 +108,7 @@ TEST(layer_norm_x86, run_test) {
   for (int i = 0; i < begin_norm_axis; ++i) {
     pre *= x_shape[i];
   }
-  for (int i = begin_norm_axis; i < x_shape.size(); ++i) {
+  for (size_t i = begin_norm_axis; i < x_shape.size(); ++i) {
     post *= x_shape[i];
   }
   std::vector<int64_t> scale_shape({post});
diff --git a/lite/kernels/x86/sequence_expand_as_compute.h b/lite/kernels/x86/sequence_expand_as_compute.h
index badbfac14cbeb120d23ea1174a9fc3a218b2224f..4ab1aeae02f5f54d2f9542520b4acda57c89eec2 100644
--- a/lite/kernels/x86/sequence_expand_as_compute.h
+++ b/lite/kernels/x86/sequence_expand_as_compute.h
@@ -66,8 +66,8 @@ class SequenceExpandAsCompute
     auto *out = param.out;
 
     auto &y_lod = y->lod();
-    CHECK_EQ(y_lod.size(), 1);
-    CHECK_GT(y_lod[0].size(), 1);
+    CHECK_EQ(y_lod.size(), 1u);
+    CHECK_GT(y_lod[0].size(), 1u);
 
     out->template mutable_data<T, T>();
 
diff --git a/lite/kernels/x86/sequence_reverse_compute_test.cc b/lite/kernels/x86/sequence_reverse_compute_test.cc
index 4b84241c8b19e3db57dd7ef6339496191a7486be..adf9981b242bfbb7f60989369715354cc2043685 100644
--- a/lite/kernels/x86/sequence_reverse_compute_test.cc
+++ b/lite/kernels/x86/sequence_reverse_compute_test.cc
@@ -30,7 +30,7 @@ static void sequence_reverse_ref(const lite::Tensor* x, lite::Tensor* y) {
   auto seq_offset = x->lod()[x->lod().size() - 1];
   int width = x->numel() / x->dims()[0];
   auto* y_data = y->mutable_data<float>();
-  for (int i = 0; i < seq_offset.size() - 1; ++i) {
+  for (size_t i = 0; i < seq_offset.size() - 1; ++i) {
     auto start_pos = seq_offset[i];
     auto end_pos = seq_offset[i + 1];
     for (auto pos = start_pos; pos < end_pos; ++pos) {
diff --git a/lite/kernels/x86/shape_compute.h b/lite/kernels/x86/shape_compute.h
index e78684e629727fc7023e6ae4c3385f9c58d48a6b..bceae79ea17665c02981666aef0cdf7827f0c45d 100644
--- a/lite/kernels/x86/shape_compute.h
+++ b/lite/kernels/x86/shape_compute.h
@@ -31,7 +31,7 @@ class ShapeCompute : public KernelLite<TARGET(kX86), PRECISION(kFloat)> {
     // auto& context = context_->As<X86Context>();
     auto out_data = param.Out->template mutable_data<int32_t>();
     auto in_dims = param.X->dims();
-    for (int i = 0; i < in_dims.size(); ++i) {
+    for (size_t i = 0; i < in_dims.size(); ++i) {
       out_data[i] = in_dims[i];
     }
   }
diff --git a/lite/kernels/x86/slice_compute.h b/lite/kernels/x86/slice_compute.h
index 0bb9fd66eb60ca1df698dbe806bc8e9ee2a69f0e..ad30215691cde66ab1c7c8c57930fc6d58de7cd5 100644
--- a/lite/kernels/x86/slice_compute.h
+++ b/lite/kernels/x86/slice_compute.h
@@ -118,7 +118,7 @@ void slice_compute(const lite::Tensor* in,
         out_dims[decrease_axis[i]] = 0;
       }
 
-      for (int i = 0; i < out_dims.size(); ++i) {
+      for (size_t i = 0; i < out_dims.size(); ++i) {
         if (out_dims[i] != 0) {
           new_out_shape.push_back(out_dims[i]);
         }
diff --git a/lite/kernels/x86/slice_compute_test.cc b/lite/kernels/x86/slice_compute_test.cc
index 8d35534f824504a965f8ded0ef82878c03739a36..a69bfc9a43c3a83f52dab8e2752921be1069252b 100644
--- a/lite/kernels/x86/slice_compute_test.cc
+++ b/lite/kernels/x86/slice_compute_test.cc
@@ -34,10 +34,10 @@ static void slice_ref(const float* input,
   std::vector<int> real_starts(in_dims.size(), 0);
   std::vector<int> real_ends(in_dims.size(), 0);
   std::vector<int> real_step(in_dims.size(), 0);
-  for (int i = 0; i < in_dims.size(); i++) {
+  for (size_t i = 0; i < in_dims.size(); i++) {
     real_ends[i] = in_dims[i];
   }
-  for (int i = 0; i < axes.size(); i++) {
+  for (size_t i = 0; i < axes.size(); i++) {
     int dim_value = in_dims[axes[i]];
     if (dim_value > 0) {
       int start = starts[i] < 0 ? (starts[i] + dim_value) : starts[i];
@@ -52,11 +52,11 @@ static void slice_ref(const float* input,
   }
   const int LEN = in_dims.size();
   int dst_step[LEN];
-  for (int i = 0; i < in_dims.size(); ++i) {
+  for (size_t i = 0; i < in_dims.size(); ++i) {
     dst_step[i] = 1;
   }
   int src_step[LEN];
-  for (int i = 0; i < in_dims.size(); ++i) {
+  for (size_t i = 0; i < in_dims.size(); ++i) {
     src_step[i] = 1;
   }
   int out_num = out_dims[in_dims.size() - 1];
@@ -69,7 +69,7 @@ static void slice_ref(const float* input,
   for (int dst_id = 0; dst_id < out_num; dst_id++) {
     int src_id = 0;
     int index_id = dst_id;
-    for (int j = 0; j < out_dims.size(); j++) {
+    for (size_t j = 0; j < out_dims.size(); j++) {
       int cur_id = index_id / dst_step[j];
       index_id = index_id % dst_step[j];
       src_id += (cur_id + real_starts[j]) * src_step[j];
@@ -409,7 +409,7 @@ void test_tensor_case3(lite::Tensor x, lite::Tensor out) {
   lite::Tensor starts_tensor, ends_tensor;
   starts_tensor.Resize(DDim({3}));
   ends_tensor.Resize(DDim({3}));
-  for (int i = 0; i < starts.size(); ++i) {
+  for (size_t i = 0; i < starts.size(); ++i) {
     starts_tensor.mutable_data<int>()[i] = starts[i];
     ends_tensor.mutable_data<int>()[i] = ends[i];
   }
diff --git a/lite/kernels/x86/stack_compute.h b/lite/kernels/x86/stack_compute.h
index 08b3515948750a5cb36627f0349c852e597619e6..6921430224a77adad0150e271ca634433700e5d6 100644
--- a/lite/kernels/x86/stack_compute.h
+++ b/lite/kernels/x86/stack_compute.h
@@ -47,7 +47,7 @@ class StackCompute : public KernelLite<TARGET(kX86), PRECISION(kFloat)> {
     int pre = 1, post = 1;
     auto dim = x[0]->dims();
     for (int i = 0; i < axis; ++i) pre *= dim[i];
-    for (int i = axis; i < dim.size(); ++i) post *= dim[i];
+    for (size_t i = axis; i < dim.size(); ++i) post *= dim[i];
 
     auto x_data_arr = x_datas.data();
 
diff --git a/lite/kernels/x86/var_conv_2d_compute.h b/lite/kernels/x86/var_conv_2d_compute.h
index 1bed39f479c87636ff217c8fd7234ea2c5bd5904..36361340ae2b2a32604fe59f3bc73c785a89028f 100644
--- a/lite/kernels/x86/var_conv_2d_compute.h
+++ b/lite/kernels/x86/var_conv_2d_compute.h
@@ -44,7 +44,7 @@ class VarConv2DCompute : public KernelLite<TARGET(kX86), PRECISION(kFloat)> {
     // 2-D lod info.
     // const auto& offset_x = in_col->lod()[0];
     // const auto& offset_y = in_row->lod()[0];
-    CHECK_EQ(param.X->lod().size(), 3) << "input lod size should be 3!";
+    CHECK_EQ(param.X->lod().size(), 3u) << "input lod size should be 3!";
     const auto& offset_y = param.X->lod()[1];
     const auto& offset_x = param.X->lod()[2];
 
diff --git a/lite/model_parser/model_parser_test.cc b/lite/model_parser/model_parser_test.cc
index d9c0f501c37862236cacd2624dc70c8cf1dacc86..16794a525142ad1ad76695dd4aaac003cba32daa 100644
--- a/lite/model_parser/model_parser_test.cc
+++ b/lite/model_parser/model_parser_test.cc
@@ -107,7 +107,7 @@ TEST(ModelParser, LoadParamNaive) {
   ASSERT_EQ(bg_lod, tensor.lod());
   ASSERT_EQ(tensor.data_size(), size);
   auto* data = tensor.data<float>();
-  for (int i = 0; i < size; ++i) {
+  for (size_t i = 0; i < size; ++i) {
     EXPECT_NEAR(bg_data[i], data[i], 1e-6);
   }
 }
diff --git a/lite/operators/elementwise_ops.cc b/lite/operators/elementwise_ops.cc
index f4debc39a0d480f38e6d37e8e60d516def7f0b55..3996c933407233538a62ae9e197978f799ce06b0 100644
--- a/lite/operators/elementwise_ops.cc
+++ b/lite/operators/elementwise_ops.cc
@@ -35,7 +35,8 @@ bool ElementwiseOp::InferShapeImpl() const {
     auto out_lod = param_.Out->mutable_lod();
     *out_lod = param_.X->lod();
   } else {
-    int max_dim = (x_dim.size() > y_dim.size() ? x_dim.size() : y_dim.size());
+    size_t max_dim =
+        (x_dim.size() > y_dim.size() ? x_dim.size() : y_dim.size());
     int axis = param_.axis;
     axis = (axis == -1 ? std::abs(static_cast<int>(x_dim.size() - y_dim.size()))
                        : axis);
@@ -48,12 +49,12 @@ bool ElementwiseOp::InferShapeImpl() const {
         y_dims_array[i] = 1;
       }
       if (axis + y_dim.size() < max_dim) {
-        for (int i = axis + y_dim.size(); i < max_dim; ++i) {
+        for (size_t i = axis + y_dim.size(); i < max_dim; ++i) {
           y_dims_array[i] = 1;
         }
       }
       x_dims_array = x_dim.Vectorize();
-      for (int i = 0; i < y_dim.size(); ++i) {
+      for (size_t i = 0; i < y_dim.size(); ++i) {
         y_dims_array[i + axis] = y_dim[i];
       }
     } else {
@@ -61,16 +62,16 @@ bool ElementwiseOp::InferShapeImpl() const {
         x_dims_array[i] = 1;
       }
       if (axis + x_dim.size() < max_dim) {
-        for (int i = axis + x_dim.size(); i < max_dim; ++i) {
+        for (size_t i = axis + x_dim.size(); i < max_dim; ++i) {
           x_dims_array[i] = 1;
         }
       }
       y_dims_array = y_dim.Vectorize();
-      for (int i = 0; i < x_dim.size(); ++i) {
+      for (size_t i = 0; i < x_dim.size(); ++i) {
         x_dims_array[i + axis] = x_dim[i];
       }
     }
-    for (int i = 0; i < max_dim; i++) {
+    for (size_t i = 0; i < max_dim; i++) {
       if (x_dims_array[i] == -1 || y_dims_array[i] == -1) {
         out_dims_array[i] = -1;
       } else {
diff --git a/lite/operators/expand_op.cc b/lite/operators/expand_op.cc
index 8e40a3b236609b1e83b5224efb462a1f803764df..ccb26e71dbe5dac18ecc5220d3697c737aee1c91 100644
--- a/lite/operators/expand_op.cc
+++ b/lite/operators/expand_op.cc
@@ -27,7 +27,7 @@ bool ExpandOpLite::CheckShape() const {
   CHECK_EQ(expand_size, x_dims_size)
       << "The number of expand_times size must be qual to the rank of "
          "Input(X).";
-  CHECK_LE(param_.X->dims().size(), 6)
+  CHECK_LE(param_.X->dims().size(), 6u)
       << "The rank of Input(X) must not be greater than 6.";
   return true;
 }
diff --git a/lite/operators/fill_constant_batch_size_like_op.cc b/lite/operators/fill_constant_batch_size_like_op.cc
index 5b0ebb38e717afea4dabe011c0161248e2113a02..b14d8c59a4ecc857d84ff4debac1740ea6fddd20 100644
--- a/lite/operators/fill_constant_batch_size_like_op.cc
+++ b/lite/operators/fill_constant_batch_size_like_op.cc
@@ -22,7 +22,7 @@ namespace operators {
 bool FillConstantBatchSizeLikeOp::CheckShape() const {
   CHECK(param_.out);
   CHECK(param_.input);
-  CHECK_GT(param_.shape.size(), 0);
+  CHECK_GT(param_.shape.size(), 0u);
   CHECK_GE(param_.input_dim_idx, 0);
   CHECK_GE(param_.output_dim_idx, 0);
   return true;
diff --git a/lite/operators/fill_constant_op.cc b/lite/operators/fill_constant_op.cc
index 565c4bbd16e01af340e728e28866268c1a845760..929966d57e05c368ce0e919804270ddacc9c8f93 100644
--- a/lite/operators/fill_constant_op.cc
+++ b/lite/operators/fill_constant_op.cc
@@ -34,7 +34,7 @@ bool FillConstantOp::InferShapeImpl() const {
       out_shape.push_back(shape_tensor_data[i]);
     }
   } else if (!shape_tensor_list.empty()) {
-    for (int i = 0; i < shape_tensor_list.size(); i++) {
+    for (size_t i = 0; i < shape_tensor_list.size(); i++) {
       out_shape.push_back(shape_tensor_list[i]->data<int>()[0]);
     }
   } else if (!param_.shape.empty()) {
diff --git a/lite/operators/flatten_op.cc b/lite/operators/flatten_op.cc
index b270dbf52f9a19f574e6f8967ff93e3a013e5737..300d516d6aa86799466ce6b02fb06212df1122f4 100644
--- a/lite/operators/flatten_op.cc
+++ b/lite/operators/flatten_op.cc
@@ -32,7 +32,7 @@ bool FlattenOp::InferShapeImpl() const {
   *out_lod = param_.x->lod();
 
   int64_t outer = 1, inner = 1;
-  for (int i = 0; i < x_dims.size(); ++i) {
+  for (size_t i = 0; i < x_dims.size(); ++i) {
     if (i < axis_) {
       outer *= x_dims[i];
     } else {
diff --git a/lite/operators/interpolate_op.cc b/lite/operators/interpolate_op.cc
index 0ef22e42903842ac41e9aca010f78796b5a32fcc..a96a602764ce5ea9ac7707ea43b58476e54d23f5 100644
--- a/lite/operators/interpolate_op.cc
+++ b/lite/operators/interpolate_op.cc
@@ -48,14 +48,14 @@ bool InterpolateOp::InferShapeImpl() const {
   auto OutSize = param_.OutSize;
   auto Scale = param_.Scale;
   if (!SizeTensor.empty()) {
-    CHECK_EQ(SizeTensor.size(), 2)
+    CHECK_EQ(SizeTensor.size(), 2u)
         << "Input(SizeTensor)'size of Op(interpolate) must be 2. "
            "Attr(out_shape)'s length must be 2 for 4-D input tensor.";
     out_h = SizeTensor[0]->data<int>()[0];
     out_w = SizeTensor[1]->data<int>()[0];
   } else if (OutSize) {
     auto OutSize_dims = OutSize->dims();
-    CHECK_EQ(OutSize_dims.size(), 1) << "Input(OutSize)'s dims size must be 1";
+    CHECK_EQ(OutSize_dims.size(), 1u) << "Input(OutSize)'s dims size must be 1";
     CHECK_EQ(OutSize_dims[0], 2) << "OutSize's dim[0] must be 2";
     auto OutSize_data = OutSize->data<int>();
     out_h = OutSize_data[0];
diff --git a/lite/operators/pool_op.h b/lite/operators/pool_op.h
index 3fcf37e6348628d489e9a2097e2c8dac7eba3e3c..97f4a8a0083550fdcb0bc2d011e5e33d2d02011d 100644
--- a/lite/operators/pool_op.h
+++ b/lite/operators/pool_op.h
@@ -105,7 +105,7 @@ inline void UpdatePadding(std::vector<int> *paddings,
                           const std::vector<int> &ksize) {
   // when padding_algorithm is "VALID" or "SAME"
   if (padding_algorithm == "SAME") {
-    for (int i = 0; i < strides.size(); ++i) {
+    for (size_t i = 0; i < strides.size(); ++i) {
       int out_size = (data_dims[i + 2] + strides[i] - 1) / strides[i];
       int pad_sum =
           std::max((out_size - 1) * strides[i] + ksize[i] - data_dims[i + 2],
diff --git a/lite/operators/reduce_mean_op.cc b/lite/operators/reduce_mean_op.cc
index c5baca5e87068d267ada21854b7769bf2bc19461..0c788f35db3ce49657e6ad176f0d5f9c3c466ada 100644
--- a/lite/operators/reduce_mean_op.cc
+++ b/lite/operators/reduce_mean_op.cc
@@ -29,7 +29,7 @@ bool ReduceMeanOp::CheckShape() const {
   auto x_dims = param_.X->dims();
   int x_rank = x_dims.size();
   if (dims.size() != 0) {
-    for (int i = 0; i < dims.size(); i++) {
+    for (size_t i = 0; i < dims.size(); i++) {
       if (dims[i] < 0) {
         dims[i] = x_rank + dims[i];
       }
@@ -46,7 +46,7 @@ bool ReduceMeanOp::InferShapeImpl() const {
   bool keep_dim = param_.keep_dim;
   auto x_rank = x_dims.size();
   if (dims.size() != 0) {
-    for (int i = 0; i < dims.size(); i++) {
+    for (size_t i = 0; i < dims.size(); i++) {
       if (dims[i] < 0) {
         dims[i] = x_rank + dims[i];
       }
@@ -65,7 +65,7 @@ bool ReduceMeanOp::InferShapeImpl() const {
       out_dims.push_back(1);
     }
   } else {
-    for (int i = 0; i < x_dims.size(); i++) {
+    for (size_t i = 0; i < x_dims.size(); i++) {
       out_dims.push_back(x_dims[i]);
     }
     if (keep_dim) {
diff --git a/lite/operators/reshape_op.cc b/lite/operators/reshape_op.cc
index 5cbdd8edc31d7d45ed81176397c9b003d1e346ae..32bc91a3a0b9b852024e2e0f2ea36585e2a29892 100644
--- a/lite/operators/reshape_op.cc
+++ b/lite/operators/reshape_op.cc
@@ -70,7 +70,7 @@ bool ReshapeOp::AttachImpl(const cpp::OpDesc &opdesc, lite::Scope *scope) {
         param_.shape_tensor_vct.push_back(var->GetMutable<lite::Tensor>());
       }
     }
-    CHECK_GT(param_.shape_tensor_vct.size(), 0)
+    CHECK_GT(param_.shape_tensor_vct.size(), 0u)
         << "ShapeError: When `shape` in ReshapeOp is a list or tuple "
            "which contains Tensor, the shape's size can't be zero. "
            "But received shape's size is "
@@ -145,7 +145,7 @@ std::vector<DDim::value_type> ValidateShape(const std::vector<int> &shape,
           << "Only one input dimension of Attr(shape) can be unknown.";
       unk_dim_idx = i;
     } else if (shape[i] == copy_dim_val) {
-      CHECK_LT(static_cast<int>(i), input_dims.size())
+      CHECK_LT(i, input_dims.size())
           << "The index of dimension to copy from input shape must be less "
              "than the size of input shape.";
     } else {
diff --git a/lite/operators/search_fc_op.cc b/lite/operators/search_fc_op.cc
index 3c64f24e48f750b367b75431333401329721a9b9..71e62c2ae729b4e1516a219888b9af3f7d994428 100644
--- a/lite/operators/search_fc_op.cc
+++ b/lite/operators/search_fc_op.cc
@@ -41,11 +41,11 @@ bool SearchFcOpLite::CheckShape() const {
   CHECK_OR_FALSE(param_.Out);
 
   auto x_dims = param_.X->dims();
-  CHECK_EQ(x_dims.size(), 2) << "The rank of X(Input) should be 2.";
+  CHECK_EQ(x_dims.size(), 2u) << "The rank of X(Input) should be 2.";
   auto w_dims = param_.W->dims();
-  CHECK_EQ(w_dims.size(), 2) << "W should be 2-D tensor.";
+  CHECK_EQ(w_dims.size(), 2u) << "W should be 2-D tensor.";
   auto b_dims = param_.b->dims();
-  CHECK_EQ(b_dims.size(), 1) << "b should be 1-D tensor.";
+  CHECK_EQ(b_dims.size(), 1u) << "b should be 1-D tensor.";
   CHECK_EQ(w_dims[1], x_dims[1]) << "wrong shape: w_dims[1] != x_dims[1]";
   return true;
 }
diff --git a/lite/operators/slice_op.cc b/lite/operators/slice_op.cc
index cf7d94535cce5fa32d0f917c9d39e4746cee1c30..ecbcc5c2c5925d320c0334889634e57ed894695f 100644
--- a/lite/operators/slice_op.cc
+++ b/lite/operators/slice_op.cc
@@ -22,7 +22,7 @@ namespace operators {
 bool SliceOp::CheckShape() const {
   CHECK_OR_FALSE(param_.X);
   CHECK_OR_FALSE(param_.Out);
-  CHECK_LT(param_.X->dims().size(), 7)
+  CHECK_LT(param_.X->dims().size(), 7u)
       << "The rank of input X should be less than 7";
   return true;
 }
@@ -67,7 +67,7 @@ bool SliceOp::InferShapeImpl() const {
       }
       out_dims[decrease_axis[i]] = 0;
     }
-    for (int i = 0; i < out_dims.size(); ++i) {
+    for (size_t i = 0; i < out_dims.size(); ++i) {
       if (out_dims[i] != 0) {
         new_out_shape.push_back(out_dims[i]);
       }
@@ -108,7 +108,7 @@ bool SliceOp::AttachImpl(const cpp::OpDesc &opdesc, lite::Scope *scope) {
 
   // The priority: StartsTensor > StartsTensorList > attr(starts).
   // The priority: EndsTensor > EndsTensorList > attr(ends).
-  int starts_size, ends_size;
+  size_t starts_size, ends_size;
   if (opdesc.HasAttr("starts")) {
     param_.starts = opdesc.GetAttr<std::vector<int>>("starts");
   }
@@ -129,7 +129,7 @@ bool SliceOp::AttachImpl(const cpp::OpDesc &opdesc, lite::Scope *scope) {
       param_.StartsTensorList.push_back(
           scope->FindVar(var)->GetMutable<lite::Tensor>());
     }
-    CHECK_GT(param_.StartsTensorList.size(), 0)
+    CHECK_GT(param_.StartsTensorList.size(), 0u)
         << "StartsTensorList size can't be zero";
     starts_size = param_.StartsTensorList.size();
   }
@@ -141,7 +141,7 @@ bool SliceOp::AttachImpl(const cpp::OpDesc &opdesc, lite::Scope *scope) {
       param_.EndsTensorList.push_back(
           scope->FindVar(var)->GetMutable<lite::Tensor>());
     }
-    CHECK_GT(param_.EndsTensorList.size(), 0)
+    CHECK_GT(param_.EndsTensorList.size(), 0u)
         << "EndsTensorList size can't be zero";
     ends_size = param_.EndsTensorList.size();
   }
diff --git a/lite/operators/split_op.cc b/lite/operators/split_op.cc
index 71deb5631dd3523ebb0367b7db5e4049b785be7b..14cff7d692e3aaa37d95233931760f37c31e4526 100644
--- a/lite/operators/split_op.cc
+++ b/lite/operators/split_op.cc
@@ -67,7 +67,7 @@ bool SplitOp::InferShapeImpl() const {
     axis = param_.axis_tensor->data<int>()[0];
   }
 
-  for (int j = 0; j < outs_dims.size(); ++j) {
+  for (size_t j = 0; j < outs_dims.size(); ++j) {
     outs[j]->Resize(outs_dims[j]);
   }
 
diff --git a/lite/operators/squeeze_op.cc b/lite/operators/squeeze_op.cc
index 633a6b4d4e45fd30bd72c8dcdfbbd96b8a8e8ebe..c34ad06debb0c4bb99d083bc7938ea26b2dcac9f 100644
--- a/lite/operators/squeeze_op.cc
+++ b/lite/operators/squeeze_op.cc
@@ -28,7 +28,7 @@ static DDim GetOutputShape(const std::vector<int> &squeeze_dims,
   // Determines number of dimensions of output tensor after squeeze.
   // Mark and count the dimensions need to be squeezed
   if (num_squeeze_dims == 0) {
-    for (int idx = 0; idx < in_dims.size(); ++idx) {
+    for (size_t idx = 0; idx < in_dims.size(); ++idx) {
       if (in_dims[idx] == 1) {
         should_squeeze[idx] = true;
         ++cnt_squeezed_dims;
@@ -57,7 +57,7 @@ static DDim GetOutputShape(const std::vector<int> &squeeze_dims,
 
   // Make output dimensions
   std::vector<int64_t> output_shape(in_dims.size() - cnt_squeezed_dims, 0);
-  for (int in_idx = 0, out_idx = 0; in_idx < in_dims.size(); ++in_idx) {
+  for (size_t in_idx = 0, out_idx = 0; in_idx < in_dims.size(); ++in_idx) {
     if (!should_squeeze[in_idx]) {
       output_shape[out_idx++] = in_dims[in_idx];
     }
diff --git a/lite/operators/unsqueeze_op.cc b/lite/operators/unsqueeze_op.cc
index b5ae90248abb4f2496a4dbca1c12317cf3a7d325..0a7487d34eeb6fe149f956e2f48bdb411a690f14 100644
--- a/lite/operators/unsqueeze_op.cc
+++ b/lite/operators/unsqueeze_op.cc
@@ -75,7 +75,7 @@ bool UnsqueezeOp::InferShapeImpl() const {
     final_axes = std::vector<int>(axes_tensor_data,
                                   axes_tensor_data + axes_tensor->numel());
   } else if (!axes_tensor_vct.empty()) {
-    for (int i = 0; i < axes_tensor_vct.size(); i++) {
+    for (size_t i = 0; i < axes_tensor_vct.size(); i++) {
       final_axes.push_back(axes_tensor_vct[i]->data<int>()[0]);
     }
   } else {