: <a>
: <b id="1">
: <c name="apple">
: </c>
: </b>
: <b id="2">
: <c name="banana">
: </c>
: </b>
: </a>
已經找到解決方法，自己來回一下，
XmlDocument doc = new XmlDocument();
doc.Load(Server.MapPath("data.xml"));
XmlNode aRoot = doc.SelectSingleNode("a");
XmlNodeList aNodeList = root.ChildNodes;
foreach (XmlNode node in aNodeList)
{
XmlNode bRoot = node;
XmlNodeList bNodeList = nRoot.ChildNodes;
TextBox1.Text += "我是B，id=" + bRoot.Attributes["id"].Value + "\n";
foreach (XmlNode node in bNodeList)
{
XmlNode cRoot = node;
TextBox1.Text += "我是C，name="
+ cRoot.Attributes["name"].Value + "\n";
}
}
也謝謝來信的板友，感恩喔