类定义于如下

     public abstract class WXResponse
    {
        [DataMember(Name="touser")]
        public String ToUserName
        {
            get;
            set;
        }

        public String FromUserName
        {
            get;
            set;
        }

        public DateTime CreateTime
        {
            get;
            set;
        }

    }


    [DataContract]
    public class ArticleResponse:WXResponse
    {
        private List<ArticleItem> Articles = new List<ArticleItem>();

        public class ArticleItem
        {
            [DataMember(Name = "title")]
            public String Title
            {
                get;
                set;
            }
            [DataMember(Name = "description")]
            public String Description
            {
                get;
                set;
            }
            [DataMember(Name = "picurl")]
            public String PicUrl
            {
                get;
                set;
            }
            [DataMember(Name = "url")]
            public String Url
            {
                get;
                set;
            }
        }

        public int ArticleCount
        {
            get
            {
                return Articles.Count;
            }
        }

        public void AddItem(String title,
            String Description,
            String PicUrl,
            String url)
        {
            Articles.Add(new ArticleItem() {
                Title = title,
                Description = Description,
                PicUrl = PicUrl,
                Url = url,
            });
        }

        [DataMember(Name="msgtype")]
        public String MsgType
        {
            get {
                return "news";
            }
            set { 
                
            }

        }
        [DataMember(Name="articles"  )]
        public List<ArticleItem> News
        {
            get {
                return Articles;
            }
        }

    }

{
    "touser":"OPENID",
    "msgtype":"news",
    "news":{
        "articles": [
         {
             "title":"Happy Day",
             "description":"Is Really A Happy Day",
             "url":"URL",
             "picurl":"PIC_URL"
         },
         {
             "title":"Happy Day",
             "description":"Is Really A Happy Day",
             "url":"URL",
             "picurl":"PIC_URL"
         }
         ]
    }
}

关键是那个news 下的 Article