diff --git a/czsc/traders/weight_backtest.py b/czsc/traders/weight_backtest.py
index 1684bd096..ea989c8cb 100644
--- a/czsc/traders/weight_backtest.py
+++ b/czsc/traders/weight_backtest.py
@@ -209,7 +209,8 @@ def __init__(self, dfw, digits=2, **kwargs) -> None:
         self.fee_rate = kwargs.get('fee_rate', 0.0002)
         self.dfw['weight'] = self.dfw['weight'].astype('float').round(digits)
         self.symbols = list(self.dfw['symbol'].unique().tolist())
-        self.results = self.backtest(n_jobs=kwargs.get('n_jobs', int(cpu_count() / 2)))
+        default_n_jobs = min(cpu_count() // 2, len(self.symbols))
+        self.results = self.backtest(n_jobs=kwargs.get('n_jobs', default_n_jobs))
 
     def get_symbol_daily(self, symbol):
         """获取某个合约的每日收益率