<?xml version="1.0" encoding="gb2312"?>
<bookstore>
  <book genre="李1" ISBN="2-3645-4">
    <title>Net从入门到精通</title>
    <author>李大蒜</author>
    <price>58.3</price>
  </book>
  <book genre="李2" ISBN="2-3631-4">
    <title>CS从入门到精通</title>
    <author>候捷</author>
    <price>58.3</price>
  </book>
  <book genre="李3" ISBN="2-3631-4">
    <title>CS从入门到精通</title>
    <author>候捷</author>
    <price>58.3</price>
  </book>
</bookstore>

执行代码一：

        /// <summary>
        /// 删除属性值等于“AttributeValue”的节点
        /// </summary>
        /// <param name="xmlFileName">XML文档完全文件名(包含物理路径)</param>
        /// <param name="xpath">要匹配的XPath表达式(例如:"//节点名//子节点名</param>
        /// <param name="xmlAttributeName">要删除包含xmlAttributeName属性的节点的名称</param>
        /// <param name="AttributeValue"></param>
        private void XmlNodeByXPath(string xmlFileName, string xpath, string xmlAttributeName, string AttributeValue)
        {
            XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.Load(xmlFileName);
            XmlNodeList xNodes = xmlDoc.SelectSingleNode(xpath).ChildNodes;
            for (int i = xNodes.Count - 1; i >= 0; i--)
            {
                XmlElement xe = (XmlElement)xNodes[i];
                if (xe.GetAttribute(xmlAttributeName) == AttributeValue)
                {
                    xNodes[i].ParentNode.RemoveChild(xNodes[i]);
                }
            }
            xmlDoc.Save(xmlFileName);
        }

实验：XmlNodeByXPath("E:\\bookstore.xml", "bookstore", "genre", "李3");

结果：

<?xml version="1.0" encoding="gb2312"?>
<bookstore>
  <book genre="李1" ISBN="2-3645-4">
    <title>Net从入门到精通</title>
    <author>李大蒜</author>
    <price>58.3</price>
  </book>
  <book genre="李2" ISBN="2-3631-4">
    <title>CS从入门到精通</title>
    <author>候捷</author>
    <price>58.3</price>
  </book>
</bookstore>

小注：

1、删除节点不能使用foreach，使用的话会造成删除XML一个节点，就跳出循环，也不报错，很隐蔽的错误。

2、该函数也可以这么实现

 	/// <summary>
        /// 删除属性值等于“AttributeValue”的节点
        /// </summary>
        /// <param name="xmlFileName">XML文档完全文件名(包含物理路径)</param>
        /// <param name="xpath">要匹配的XPath表达式(例如:"//节点名//子节点名</param>
        /// <param name="xmlAttributeName">要删除包含xmlAttributeName属性的节点的名称</param>
        /// <param name="AttributeValue"></param>
        private void XmlNodeByXPath(string xmlFileName, string xpath, string xmlAttributeName, string AttributeValue)
        {
            XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.Load(xmlFileName);
            XmlNode root = xmlDoc.SelectSingleNode(xpath);
            XmlNodeList xnl = xmlDoc.SelectSingleNode(xpath).ChildNodes;
            for (int i = 0; i < xnl.Count; i++)
            {
                XmlElement xe = (XmlElement)xnl.Item(i);
                if (xe.GetAttribute(xmlAttributeName) == AttributeValue)
                {
                    root.RemoveChild(xe);
                    if (i < xnl.Count) i = i - 1;
                }
            }
            xmlDoc.Save(xmlFileName);   
        }