public static string XmlSerialize(T obj)
{
       using (StringWriter sw = new StringWriter())
       {
             Type t= obj.GetType();             
             XmlSerializer serializer = new XmlSerializer(obj.GetType());
             serializer.Serialize(sw, obj);
             sw.Close();
             return sw.ToString();
        }
}

[System.Xml.Serialization.XmlTypeAttribute(AnonymousType = true)]
    [System.Xml.Serialization.XmlRootAttribute(Namespace = "", IsNullable = false)]
    public class Request
    {

        public string System { get; set; }
        public string SecurityCode { get; set; }
        public PatientBasicInfo PatientInfo { get; set; }
    }

    /// 
    [System.Xml.Serialization.XmlTypeAttribute(AnonymousType = true)]
    public partial class PatientBasicInfo
    {
        public string PatientNo { get; set; }
        public string PatientName { get; set; }
        public string Phoneticize { get; set; }
        public string Sex { get; set; }
        public string Birth { get; set; }
        public string BirthPlace { get; set; }
        public string Country { get; set; }
        public string Nation { get; set; }
        public string IDNumber { get; set; }
        public string SecurityNo { get; set; }
        public string Workunits { get; set; }
        public string Address { get; set; }
        public string ZIPCode { get; set; }
        public string Phone { get; set; }
        public string ContactPerson { get; set; }
        public string ContactShip { get; set; }
        public string ContactPersonAdd { get; set; }
        public string ContactPersonPhone { get; set; }
        public string OperationCode { get; set; }
        public string OperationName { get; set; }
        public string OperationTime { get; set; }
        public string CardNo { get; set; }
        public string ChangeType { get; set; }

    }

Request patientIn = new Request();
            patientIn.System = "HIS";
            patientIn.SecurityCode = "HIS5";

            PatientBasicInfo basicInfo = new PatientBasicInfo();
            basicInfo.PatientNo = "1234";
            basicInfo.PatientName = "測試";
            basicInfo.Phoneticize = "";
            basicInfo.Sex = "1";
            basicInfo.Birth = "";
            basicInfo.BirthPlace = "";
            basicInfo.Country = "";
            basicInfo.Nation = "";
            basicInfo.IDNumber = "";
            basicInfo.SecurityNo = "";
            basicInfo.Workunits = "";
            basicInfo.Address = "";
            basicInfo.ZIPCode = "";
            basicInfo.Phone = "";
            basicInfo.ContactShip = "";
            basicInfo.ContactPersonPhone = "";
            basicInfo.ContactPersonAdd = "";
            basicInfo.ContactPerson = "";
            basicInfo.ChangeType = "";
            basicInfo.CardNo = "";
            basicInfo.OperationCode = "";
            basicInfo.OperationName = "";
            basicInfo.OperationTime = "";

            patientIn.PatientInfo = basicInfo;

            //序列化
            string strxml = XmlSerializeHelper.XmlSerialize(patientIn);

  HIS
  HIS5
  
    1234
    測試
    
    1
    
    
    
    
    
    
    
    

    
    
    
    
    
    
    
    
    
    
    
  

public static T DESerializer(string strXML) where T:class
{
     try
    {
            using (StringReader sr = new StringReader(strXML))
           {
                XmlSerializer serializer = new XmlSerializer(typeof(T));
                return serializer.Deserialize(sr) as T;
           }
     }
     catch (Exception ex)
     {
            return null;
     }
}

//反序列化
Request r = XmlSerializeHelper.DESerializer(strxml);

//將DataTable轉換成XML
DataTable dt = new DataTable("MyTable");
//添加列
dt.Columns.Add("Id", typeof(int));
dt.Columns.Add("Name", typeof(string));
dt.Columns.Add("Sex", typeof(char));
//添加行
dt.Rows.Add(1, "小明", '1');
dt.Rows.Add(2, "小紅", '2');
dt.Rows.Add(3, "小王", '2');
dt.Rows.Add(4, "測試", '2');
//序列化，將DataTable轉換成XML格式的字符串
string strXML = XmlSerializeHelper.XmlSerialize  (dt);

//反序列化，將XML轉換成字符串
DataTable dtNew=  XmlSerializeHelper.DESerializer(strXML);

/// 

/// 測試類
/// 
public class Student
{
    public int Id { get; set; }
    public string Name { get; set; }
    public char Sex { get; set; }
    public int Age { get; set; }
}

//測試集合
List list = new List()
{
        new Student(){Id=1,Name="小紅",Sex='2',Age=20},
        new Student(){Id=2,Name="小明",Sex='1',Age=22},
        new Student(){Id=3,Name="小王",Sex='1',Age=19},
        new Student(){Id=4,Name="測試",Sex='2',Age=23}
};
//序列化
string strXML = XmlSerializeHelper.XmlSerialize>(list);

//反序列化
List listStu = XmlSerializeHelper.DESerializer>(strXML);