diff --git a/metagpt/provider/openai_api.py b/metagpt/provider/openai_api.py
index dd5594b7d..64fbbdfd6 100644
--- a/metagpt/provider/openai_api.py
+++ b/metagpt/provider/openai_api.py
@@ -286,13 +286,17 @@ class OpenAIGPTAPI(BaseGPTAPI, RateLimiter):
         windows = []
         idx = 0
         while idx < total_len:
-            data_len = window_size - padding_size
-            if data_len + idx > total_len:
+            if window_size + idx > total_len:  # 不足一个滑窗
                 windows.append(text[idx:])
                 break
-            w = text[idx : idx + data_len]
+            # 第一个窗口少算自然就可实现滑窗功能, 比如: [1, 2, 3, 4, 5, 6, 7, ....]
+            # window_size=3, padding_size=1：
+            # [1, 2, 3], [3, 4, 5], [5, 6, 7], ....
+            #   idx=2,  |  idx=5   |  idx=8  | ...
+            w = text[idx : idx + window_size]
             windows.append(w)
-            idx += data_len
+            idx += window_size - padding_size if idx == 0 else window_size
+
         for i in range(len(windows)):
             if i + 1 == len(windows):
                 break