在一个临时item班的帮助下

public class item
{
    [XmlAttribute]
    public int id;
    [XmlAttribute]
    public string value;
}

样本字典：

Dictionary<int, string> dict = new Dictionary<int, string>()
{
    {1,"one"}, {2,"two"}
};

。

XmlSerializer serializer = new XmlSerializer(typeof(item[]), 
                                 new XmlRootAttribute() { ElementName = "items" });

序列化

serializer.Serialize(stream, 
              dict.Select(kv=>new item(){id = kv.Key,value=kv.Value}).ToArray() );

反序列化

var orgDict = ((item[])serializer.Deserialize(stream))
               .ToDictionary(i => i.id, i => i.value);

--------------------------------------------------

如果您改变主意，可以 使用XElement 完成此 操作 。

序列化

XElement xElem = new XElement(
                    "items",
                    dict.Select(x => new XElement("item",new XAttribute("id", x.Key),new XAttribute("value", x.Value)))
                 );
var xml = xElem.ToString(); //xElem.Save(...);

反序列化

XElement xElem2 = XElement.Parse(xml); //XElement.Load(...)
var newDict = xElem2.Descendants("item")
                    .ToDictionary(x => (int)x.Attribute("id"), x => (string)x.Attribute("value"));