diff --git a/cocos/3d/CCSprite3D.cpp b/cocos/3d/CCSprite3D.cpp
index 6e2779ccdd..b5cb0e760c 100644
--- a/cocos/3d/CCSprite3D.cpp
+++ b/cocos/3d/CCSprite3D.cpp
@@ -464,7 +464,7 @@ void Sprite3D::setMaterial(Material *material, int meshIndex)
 
     if (meshIndex == -1)
     {
-        for (size_t i = 0; i < _meshes.size(); i++)
+        for (ssize_t i = 0; i < _meshes.size(); i++)
         {
             _meshes.at(i)->setMaterial(i == 0 ? material : material->clone());
         }
diff --git a/cocos/network/WebSocket.cpp b/cocos/network/WebSocket.cpp
index ef571822b3..ca04db0530 100644
--- a/cocos/network/WebSocket.cpp
+++ b/cocos/network/WebSocket.cpp
@@ -668,10 +668,10 @@ void WebSocket::onClientWritable()
         WsMessage* subThreadMsg = *iter;
         Data* data = (Data*)subThreadMsg->obj;
 
-        const size_t c_bufferSize = WS_RX_BUFFER_SIZE;
+        const ssize_t c_bufferSize = WS_RX_BUFFER_SIZE;
 
-        const size_t remaining = data->len - data->issued;
-        const size_t n = std::min(remaining, c_bufferSize );
+        const ssize_t remaining = data->len - data->issued;
+        const ssize_t n = std::min(remaining, c_bufferSize);
 
         WebSocketFrame* frame = nullptr;
 
diff --git a/cocos/physics3d/CCPhysics3DComponent.cpp b/cocos/physics3d/CCPhysics3DComponent.cpp
index 39907e98e8..531ad289b7 100644
--- a/cocos/physics3d/CCPhysics3DComponent.cpp
+++ b/cocos/physics3d/CCPhysics3DComponent.cpp
@@ -100,7 +100,7 @@ void Physics3DComponent::addToPhysicsWorld(Physics3DWorld* world)
         {
             auto parent = _owner->getParent();
             while (parent) {
-                for (int i = 0; i < components.size(); i++) {
+                for (size_t i = 0; i < components.size(); i++) {
                     if (parent == components[i]->getOwner())
                     {
                         //insert it here
diff --git a/cocos/ui/UIRichText.cpp b/cocos/ui/UIRichText.cpp
index 36972c9bec..44ead9a89d 100644
--- a/cocos/ui/UIRichText.cpp
+++ b/cocos/ui/UIRichText.cpp
@@ -1483,7 +1483,7 @@ static int getPrevWord(const std::string& text, int idx)
 
 static bool isWrappable(const std::string& text)
 {
-    for (int i=0; i<text.length(); ++i)
+    for (size_t i = 0; i < text.length(); ++i)
     {
         if (!std::isalnum(text[i], std::locale()))
             return true;
diff --git a/tests/cpp-tests/Classes/LabelTest/LabelTestNew.cpp b/tests/cpp-tests/Classes/LabelTest/LabelTestNew.cpp
index 1391669611..17e0b2631c 100644
--- a/tests/cpp-tests/Classes/LabelTest/LabelTestNew.cpp
+++ b/tests/cpp-tests/Classes/LabelTest/LabelTestNew.cpp
@@ -1034,7 +1034,7 @@ LabelTTFFontsTestNew::LabelTTFFontsTestNew()
     auto size = Director::getInstance()->getWinSize();
     TTFConfig ttfConfig(ttfpaths[0],20, GlyphCollection::NEHE);
 
-    for (size_t i = 0; i < fontCount; ++i) {
+    for (int i = 0; i < fontCount; ++i) {
         ttfConfig.fontFilePath = ttfpaths[i];
         auto label = Label::createWithTTF(ttfConfig, ttfpaths[i], TextHAlignment::CENTER,0);
         if( label ) {            
diff --git a/tests/cpp-tests/Classes/MaterialSystemTest/MaterialSystemTest.cpp b/tests/cpp-tests/Classes/MaterialSystemTest/MaterialSystemTest.cpp
index c5ccc29eb8..59d318f6ff 100644
--- a/tests/cpp-tests/Classes/MaterialSystemTest/MaterialSystemTest.cpp
+++ b/tests/cpp-tests/Classes/MaterialSystemTest/MaterialSystemTest.cpp
@@ -422,7 +422,7 @@ void Material_parsePerformance::parsingTesting(unsigned int count)
 {
     std::clock_t begin = std::clock();
     
-    for(int i=0;i<count;i++)
+    for (unsigned int i = 0; i < count; i++)
     {
         Material::createWithFilename("Materials/2d_effects.material");
         Material::createWithFilename("Materials/3d_effects.material");