public class Team
  {
    public string Name { get; set; }
    public List<User> Users { get; set; }
  } 
  public class User
  {
    public int Id { get; set; }
    public string Name { get; set; }
  }

JavaScriptSerializer js = new JavaScriptSerializer();
  Team team = new Team()
  {
 Name = "梦之队",
 Users = new List<User>() { 
 new User() { Id = 1, Name = "XXX" },
  new User() { Id = 2, Name = "YYY" },
  new User() { Id = 3, Name = "ZZZ" },
 }
  };
  string json = js.Serialize(team);
  Console.WriteLine(json);

  string json = "{\"Name\":\"梦之队\",\"Users\":[{\"Id\":1,\"Name\":\"XXX\"},{\"Id\":2,\"Name\":\"YYY\"},{\"Id\":3,\"Name\":\"ZZZ\"}]}";
  JavaScriptSerializer js = new JavaScriptSerializer();
  Team team = js.Deserialize<Team>(json);