diff --git a/cocos/2d/CCFontAtlas.cpp b/cocos/2d/CCFontAtlas.cpp
index 3e1448d98c..8593a0f666 100644
--- a/cocos/2d/CCFontAtlas.cpp
+++ b/cocos/2d/CCFontAtlas.cpp
@@ -251,7 +251,7 @@ void FontAtlas::findNewCharacters(const std::u16string& u16Text, std::unordered_
     else
     {
         auto length = u16Text.length();
-        newChars.resize(length);
+        newChars.reserve(length);
         for (size_t i = 0; i < length; ++i)
         {
             auto outIterator = _letterDefinitions.find(u16Text[i]);