Encoding enc = Encoding.UTF8;
        XmlWriterSettings xws = new XmlWriterSettings();
        xws.Encoding = enc;
        xws.Indent = true;
        MemoryStream ms = new MemoryStream();
        string strXml = "";
        using (XmlWriter writer = XmlWriter.Create(ms, xws))
        {
 
            writer.WriteStartDocument();
            writer.WriteStartElement("rss");
            writer.WriteAttributeString("version", "2.0");
 
            writer.WriteStartElement("channel");
 
            // channel data
            writer.WriteElementString("title", "最新文章");
            ...(XML 資料)......
 
            writer.WriteEndElement(); // channel end
 
            writer.WriteEndElement(); //rss end
            writer.WriteEndDocument();
 
            writer.Flush();
            
            StreamReader reader = new StreamReader(ms, enc, true);
            ms.Seek(0, SeekOrigin.Begin);
            strXml = reader.ReadToEnd();
        }