public class Person
    {
        public string Name
        {
            get;
            set;
        }

        public int Age
        {
            get;
            set;
        }

        public DateTime Birth
        {
            get;
            set;
        }

        public string BirthDay
        {
            get;
            set;
        }
    }

 Person person = new Person();
 person.Name = "张小晓";
 person.Age = 10;
 person.Birth = new DateTime(1990, 11, 22);
 person.BirthDay = person.Birth.ToString("yyyy-MM-dd");
 JavaScriptSerializer js = new JavaScriptSerializer();
 string result = js.Serialize(person);
 Console.WriteLine(result);
 Console.Read();