diff --git a/lib/exchange/okx_options_lib.py b/lib/exchange/okx_options_lib.py
index ecc9fae..93ed7e2 100644
--- a/lib/exchange/okx_options_lib.py
+++ b/lib/exchange/okx_options_lib.py
@@ -19,6 +19,7 @@ from lib.options.options_pricing_lib import (
 )
 
 _OKX_OPTION_ERR_ZH: dict[str, str] = {
+    "51008": "资金账户 USDT 可用余额不足",
     "51018": "期权账户不能持有净空头头寸",
     "51019": "期权买入须使用逐仓模式(全仓模式下不能持有多头净头寸)",
 }
@@ -1114,10 +1115,9 @@ def execute_convert(ex: ccxt.okx, quote_id: str) -> dict[str, Any]:
         data = (resp or {}).get("data") or []
         if data and str(data[0].get("sCode", "0")) == "0":
             return {"ok": True, "data": data[0], "raw": resp}
-        msg = data[0].get("sMsg") if data else str(resp)
-        return {"ok": False, "msg": msg or "兑换失败", "raw": resp}
+        return {"ok": False, "msg": _okx_trade_error_message(resp=resp), "raw": resp}
     except Exception as e:
-        return {"ok": False, "msg": str(e)}
+        return {"ok": False, "msg": _okx_trade_error_message(e)}
 
 
 def transfer_ccy(
@@ -1133,7 +1133,7 @@ def transfer_ccy(
         resp = ex.transfer(str(ccy).upper(), float(amount), from_account, to_account)
         return {"ok": True, "data": resp}
     except Exception as e:
-        return {"ok": False, "msg": str(e)}
+        return {"ok": False, "msg": _okx_trade_error_message(e)}
 
 
 _OKX_ACCT_CODE = {"funding": "6", "trading": "18", "spot": "18"}
@@ -1199,10 +1199,9 @@ def spot_market_swap_usdt_usdc(
         data = (resp or {}).get("data") or []
         if data and str(data[0].get("sCode")) == "0":
             return {"ok": True, "data": data[0], "raw": resp}
-        msg = data[0].get("sMsg") if data else str(resp)
-        return {"ok": False, "msg": msg or "现货兑换失败", "raw": resp}
+        return {"ok": False, "msg": _okx_trade_error_message(resp=resp), "raw": resp}
     except Exception as e:
-        return {"ok": False, "msg": str(e)}
+        return {"ok": False, "msg": _okx_trade_error_message(e)}
 
 
 def transfer_main_sub_account(
@@ -1237,10 +1236,9 @@ def transfer_main_sub_account(
         data = (resp or {}).get("data") or []
         if data and str(data[0].get("sCode", "0")) == "0":
             return {"ok": True, "data": data[0], "raw": resp}
-        msg = data[0].get("sMsg") if data else str(resp)
-        return {"ok": False, "msg": msg or "主/子账户划转失败", "raw": resp}
+        return {"ok": False, "msg": _okx_trade_error_message(resp=resp), "raw": resp}
     except Exception as e:
-        return {"ok": False, "msg": str(e)}
+        return {"ok": False, "msg": _okx_trade_error_message(e)}
 
 
 def format_position_row(
diff --git a/tests/test_okx_spot_swap.py b/tests/test_okx_spot_swap.py
index 7b7e72f..9de2608 100644
--- a/tests/test_okx_spot_swap.py
+++ b/tests/test_okx_spot_swap.py
@@ -30,6 +30,16 @@ class TestOkxSpotSwap(unittest.TestCase):
         self.assertEqual(body["tgtCcy"], "base_ccy")
         self.assertEqual(body["side"], "sell")
 
+    def test_insufficient_balance_returns_chinese_message(self):
+        ex = MagicMock()
+        ex.private_post_trade_order.side_effect = Exception(
+            'okx {"code":"1","data":[{"sCode":"51008","sMsg":"Order failed. Your available USDT balance is insufficient."}]}'
+        )
+        result = spot_market_swap_usdt_usdc(ex, direction="usdt_to_usdc", amount=20)
+        self.assertFalse(result["ok"])
+        self.assertEqual(result["msg"], "资金账户 USDT 可用余额不足")
+        self.assertNotIn("{", result["msg"])
+
 
 if __name__ == "__main__":
     unittest.main()