public class TData { public int Id { get; set; } public string StuName { get; set; } public string ClsName { get; set; } public decimal Score { get; set; } } public class ToolTest { [Fact] public void Test() { var list = new List<TData> { new TData() { Id = 1, StuName = "zhangsan", ClsName = "1", Score = 70 }, new TData() { Id = 2, StuName = "lisi", ClsName = "1", Score = 80 }, new TData() { Id = 3, StuName = "wangwu", ClsName = "1", Score = 90 }, new TData() { Id = 4, StuName = "liaoliu", ClsName = "1", Score = 100 }, new TData() { Id = 5, StuName = "zhangsan", ClsName = "2", Score = 90 }, new TData() { Id = 6, StuName = "lisi", ClsName = "2", Score = 40 }, new TData() { Id = 7, StuName = "wangwu", ClsName = "2", Score = 50 }, new TData() { Id = 8, StuName = "liaoliu", ClsName = "2", Score = 60 }, }; //var g = list.GroupBy(g => g.ClsName); var resut1 = list.GroupBy(g => g.ClsName).Select(s => s.Select(s => s.Score).Max()); var resut2 = list.GroupBy(g => g.ClsName).Select(s => s.OrderByDescending(o => o.Score).FirstOrDefault()); } }