using (MemoryStream ms = new MemoryStream())
            {

XmlWriterSettings settings = new XmlWriterSettings();

//要求缩进

settings.Indent = true;

//注意如果不设置encoding默认将输出utf-16 
                //注意这儿不能直接用Encoding.UTF8如果用Encoding.UTF8将在输出文本的最前面添加3个字节的非xml内容 
                settings.Encoding = Encoding.UTF8;
                //settings.Encoding = new UTF8Encoding(false);

//设置换行符 
                settings.NewLineChars = Environment.NewLine;

using (XmlWriter xmlWriter = XmlWriter.Create(ms, settings))
                {
                    //写xml文件开始<?xml version="1.0" encoding="utf-8" ?> 
                     xmlWriter.WriteStartDocument(false);

//写根节点 
                    xmlWriter.WriteStartElement("root");

//写字节点 
                    xmlWriter.WriteStartElement("cat");

//给节点添加属性 
                    xmlWriter.WriteAttributeString("color", "white");

//给节点内部添加文本 
                    xmlWriter.WriteString("I'm a cat");

xmlWriter.WriteEndElement();

//通过WriteElementString可以添加一个节点同时添加节点内容 
                    xmlWriter.WriteElementString("pig", "pig is great");

xmlWriter.WriteStartElement("dog");

//写CData 
                    xmlWriter.WriteCData("<strong>dog is dog</strong>");
                    xmlWriter.WriteEndElement();

xmlWriter.WriteComment("this is an example writed by bob");

xmlWriter.WriteEndElement();
                    xmlWriter.WriteEndDocument();
                }

//将xml内容输出到控制台中 
                string xml = Encoding.UTF8.GetString(ms.ToArray());
                Console.WriteLine(xml);

}

Console.Read();

}