array = lst.ToArray(); //注意Parallel.ForEach 里面传的是数组， MaxDegreeOfParallelism = Environment.ProcessorCount指的是系统有几个cpu就使用几个cpu ParallelLoopResult result = Parallel.ForEach(array, new ParallelOptions { MaxDegreeOfParallelism = Environment.ProcessorCount },item = item.Uname = "张" + item.Age; foreach (var item in array) Console.WriteLine("循环更改后的值：" + item.Id + "," + item.Age + "," + item.Uname); Console.ReadKey(); }