diff --git a/be/src/exprs/string_functions.cpp b/be/src/exprs/string_functions.cpp
index 233be37c2b..1c95f2f57a 100644
--- a/be/src/exprs/string_functions.cpp
+++ b/be/src/exprs/string_functions.cpp
@@ -120,6 +120,7 @@ StringVal StringFunctions::substring(FunctionContext* context, const StringVal&
 //    string left(string input, int len)
 // This behaves identically to the mysql implementation.
 StringVal StringFunctions::left(FunctionContext* context, const StringVal& str, const IntVal& len) {
+    if (len.val >= str.len)  return str;
     return substring(context, str, 1, len);
 }
 
diff --git a/be/test/exprs/string_functions_test.cpp b/be/test/exprs/string_functions_test.cpp
index fe894cda66..010c1e3ef3 100644
--- a/be/test/exprs/string_functions_test.cpp
+++ b/be/test/exprs/string_functions_test.cpp
@@ -287,6 +287,13 @@ TEST_F(StringFunctionsTest, null_or_empty) {
     delete context;
 }
 
+TEST_F(StringFunctionsTest, left) {
+    doris_udf::FunctionContext* context = new doris_udf::FunctionContext();
+
+    ASSERT_EQ(AnyValUtil::from_string(ctx, std::string("")),
+              StringFunctions::left(context, StringVal(""), 10));
+}
+
 TEST_F(StringFunctionsTest, substring) {
     doris_udf::FunctionContext* context = new doris_udf::FunctionContext();