diff --git a/err_group/weather.go b/err_group/weather.go
index 1ebe5d2..6793db1 100644
--- a/err_group/weather.go
+++ b/err_group/weather.go
@@ -47,13 +47,13 @@ func GetAllCityWeatherData(timeOut time.Duration) ([]*WeatherData, error) {
 	// 创建一个携带cancel的context
 	ctx, cancel := context.WithTimeout(context.Background(), timeOut)
 	defer cancel() // 确保所有路径都调用cancel
-	list := make([]*WeatherData, 0)
 
 	// 初始化一个ErrGroup对象
 	g, ctx := errgroup.WithContext(ctx)
 
 	// 城市列表
 	cities := []string{"New York", "Tokyo", "Berlin", "Paris", "Beijing"}
+	list := make([]*WeatherData, 0, len(cities))
 
 	// 循环启动goroutine来获取每个城市的天气数据
 	for _, city := range cities {