diff --git a/mybatis-flex-core/src/main/java/com/mybatisflex/core/util/StringUtil.java b/mybatis-flex-core/src/main/java/com/mybatisflex/core/util/StringUtil.java
index 2c3566cf..edbd7ab3 100644
--- a/mybatis-flex-core/src/main/java/com/mybatisflex/core/util/StringUtil.java
+++ b/mybatis-flex-core/src/main/java/com/mybatisflex/core/util/StringUtil.java
@@ -88,14 +88,16 @@ public class StringUtil {
         if (isBlank(string)) {
             return "";
         }
-        String temp = string.toLowerCase();
-        int strLen = temp.length();
+        if(Character.isUpperCase(string.charAt(0))){
+            string = string.toLowerCase();
+        }
+        int strLen = string.length();
         StringBuilder sb = new StringBuilder(strLen);
         for (int i = 0; i < strLen; i++) {
-            char c = temp.charAt(i);
+            char c = string.charAt(i);
             if (c == '_') {
                 if (++i < strLen) {
-                    sb.append(Character.toUpperCase(temp.charAt(i)));
+                    sb.append(Character.toUpperCase(string.charAt(i)));
                 }
             } else {
                 sb.append(c);