diff --git a/metagpt/actions/execute_code.py b/metagpt/actions/execute_code.py
index 1d20bf3f6..36e01ed0e 100644
--- a/metagpt/actions/execute_code.py
+++ b/metagpt/actions/execute_code.py
@@ -186,14 +186,13 @@ class ExecutePyCode(ExecuteCode, Action):
 def truncate(result: str, keep_len: int = 2000) -> str:
     desc = f"Truncated to show only the last {keep_len} characters\n"
     if result.startswith(desc):
-        result = result[-len(desc) :]
+        result = result[len(desc) :]
 
     if len(result) > keep_len:
         result = result[-keep_len:]
-
-    if not result.startswith(desc):
         return desc + result
-    return desc
+
+    return result
 
 
 def remove_escape_and_color_codes(input_str):
diff --git a/tests/metagpt/actions/test_execute_code.py b/tests/metagpt/actions/test_execute_code.py
index 73b5886dc..95f883e12 100644
--- a/tests/metagpt/actions/test_execute_code.py
+++ b/tests/metagpt/actions/test_execute_code.py
@@ -1,6 +1,6 @@
 import pytest
 
-from metagpt.actions.execute_code import ExecutePyCode
+from metagpt.actions.execute_code import ExecutePyCode, truncate
 from metagpt.schema import Message
 
 
@@ -81,3 +81,10 @@ async def test_plotting_bug():
     pi = ExecutePyCode()
     output = await pi.run(code)
     assert output[1] is True
+
+
+def test_truncate():
+    output = "hello world"
+    assert truncate(output) == output
+    output = "hello world"
+    assert truncate(output, 5) == "Truncated to show only the last 5 characters\nworld"