Configuration configuration = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);  configuration.AppSettings.Settings["节点名称"].Value ="0";  configuration.Save(ConfigurationSaveMode.Modified);  

//获取config路径    string path = System.Windows.Forms.Application.ExecutablePath + ".config";    XDocument doc = XDocument.Load(path);    //查找所有节点    IEnumerable<XElement> element = doc.Element("configuration").Element("appSettings").Elements();    //遍历节点    foreach (XElement item in element)    {        if (item.Attribute("key") != null && item.Attribute("key").Value == "节点名称")        {            if (item.Attribute("value") != null)            {   item.Attribute("value").SetValue(DateTime.Now.ToString("d"));            }        }    }    //保存    doc.Save(path);