MVC一樣適用，我用的是nuget下載的newtonsoft.json

using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Text;

namespace MVC_A
{
    class Program
    {
        static void Main(string[] args)
        {
            myobjclass myObj = new myobjclass(new List<parameter>{
                new parameter("h_CAM_action", "logonAs"),
                new parameter("CAMNamespace", "JDBCAuth"),
                new parameter("CAMUsername", "ABCD"),
                new parameter("CAMPassword", "ABCD"),
            });
            Console.WriteLine(JsonConvert.SerializeObject(myObj));
            Console.ReadKey();// 等你按任一鍵
            POST(new Uri("https://test.abcd.com/a.php"),myObj);
        }

        private static void POST(Uri servSite, myobjclass myObj)
        {
            using (WebClient wc = new WebClient())
            {
                try
                {
                    wc.Encoding = Encoding.UTF8;
                    var res = wc.UploadString(servSite,JsonConvert.SerializeObject(myObj) );
                    Console.WriteLine(res);
                }
                catch (WebException ex)
                {
                    throw new Exception("無法連接遠端伺服器");
                }
            }
        }
    }
    class myobjclass
    {
        public List<parameter> parameters { get; set; }
        public myobjclass(List<parameter> initValue)
        {
            parameters = new List<parameter>();
            if (initValue.Any())
                parameters.AddRange(initValue);
        }
    }
    class parameter
    {
        public string name { get; set; }
        public string value { get; set; }
        public parameter(string _name, string _value)
        {
            name = _name;
            value = _value;
        }
    }
}