//这是一个webservice

private AppUpdate.UpdateServ  UpdateSvr;

  private void button1_Click(object sender, System.EventArgs e)
  {
   
   if(LinkWebServices()==true)
   {
    this.label1.Text="连接服务器....... PASS";
   
    if(CheckVer()==true)
    {
     this.label2.Text="检查最新版本并下载.......PASS";
                  
    }
    else
    {
     this.label2.Text="检查最新版本并下载.......FAIL";
    }
   }
   else
   {
    this.label1.Text="连接服务器.......FAIL";
   }
  }

//这是用来与升级服务器建立连接
  private bool LinkWebServices()
  {
   try
   {
    UpdateSvr=new UpdateServ();
    return true;
   }
   catch
   {
    return false;
   }
  }

//调用webservice用来检查是不是有最新的版本
  private bool CheckVer()
  {
   string path =Application.StartupPath;
   try
   {
    VersionCheck(path);
    return true;
   }
   catch(Exception ex)
   {
    MessageBox.Show(ex.ToString());
    return false;
   }
  }

  private void VersionCheck(string desPath)
  {
   try
   {
    #region 查看文件和目录
    if(!desPath.EndsWith(@"\"))
     desPath += @"\";

    if(!System.IO.Directory.Exists(desPath))
    {
     System.IO.Directory.CreateDirectory(desPath);
    }

    string tempPath = desPath + @"tempDesPathCache\";

    if(System.IO.Directory.Exists(tempPath))
    {
     System.IO.Directory.Delete(tempPath,true);
     System.IO.Directory.CreateDirectory(tempPath);
    }
    else
     System.IO.Directory.CreateDirectory(tempPath);

    if(!System.IO.File.Exists(desPath + "UpdateConfig.xml"))
    {
     System.Xml.XmlDocument updateConfig = new System.Xml.XmlDocument();
     updateConfig.LoadXml(@"<root></root>");
     updateConfig.Save(desPath + "UpdateConfig.xml");
    }
    #endregion

  
    System.Xml.XmlDocument serverXmlDoc = UpdateSvr.AppUpdateVertion();
    System.Xml.XmlDocument localXmlDoc = new System.Xml.XmlDocument();
    localXmlDoc.Load(desPath + "UpdateConfig.xml");
    bool newVersionExist = false;
    bool moduleExist = false;
    System.Xml.XmlNode serverNode0 = serverXmlDoc.ChildNodes[0];
    System.Xml.XmlNode localNode0 = localXmlDoc.ChildNodes[0];
    foreach(System.Xml.XmlNode serverNode in serverNode0)
    {
     moduleExist = false;
     foreach(System.Xml.XmlNode localNode in localNode0)
     {
      //找到对应模块
      if(localNode.ChildNodes[0].InnerText == serverNode.ChildNodes[0].InnerText)
      {
       moduleExist = true;
       //版本号判断
       if(localNode.ChildNodes[1].InnerText.CompareTo(serverNode.ChildNodes[1].InnerText) < 0)
       {
        newVersionExist = true;
        if(System.Configuration.ConfigurationSettings.AppSettings["NetStyle"].ToString()=="internet")
        {
         DownloadFile(serverNode.ChildNodes[2].InnerText,tempPath + serverNode.ChildNodes[0].InnerText);
        }
        else
        {
         DownloadFile(serverNode.ChildNodes[3].InnerText,tempPath + serverNode.ChildNodes[0].InnerText);
        }
       }
       break;
      }
     }
     //没找到对应模块
     if(false == moduleExist)
     {
     
      if(System.Configuration.ConfigurationSettings.AppSettings["NetStyle"].ToString()=="internet")
      {
       DownloadFile(serverNode.ChildNodes[2].InnerText,tempPath + serverNode.ChildNodes[0].InnerText);
      }
      else
      {
       DownloadFile(serverNode.ChildNodes[3].InnerText,tempPath + serverNode.ChildNodes[0].InnerText);
      }
     }
    }
    //写入新UpdateConfig.xml升级完毕后替换
    if(newVersionExist)
    {
     serverXmlDoc.Save(tempPath + "UpdateConfig.xml");
     if(DialogResult.Yes == MessageBox.Show("有新版本，是否更新?","提示",MessageBoxButtons.YesNo))
     {
      string[] dirs = System.IO.Directory.GetFiles(tempPath, "*.*");
      string fileName;
      foreach (string dir in dirs)
      {
       fileName = ((dir.Split(Convert.ToChar(@"\")))[dir.Split(Convert.ToChar(@"\")).Length - 1]);
       if(System.IO.File.Exists(desPath + fileName))
       {
        //TODO:可以支持备份以前版本
        System.IO.File.Delete(desPath + fileName);
       }
       //TODO:如果系统正在运行，您得停止系统，至于如何停止，也许可以使用System.Diagnostics.Process
       System.IO.File.Move(dir,desPath + fileName);
      }
      MessageBox.Show("升级完毕");
     }
     else
     {
      //TODO:可以支持重新提示升级
     }
    }
   }
   catch(Exception ex)
   {
    throw new Exception("升级失败，原因是：" + ex.Message,ex);
   }
  }

//下载最新的文件

  private void DownloadFile(string source,string fileName)
  {
   try
   {
    System.Net.WebClient myWebClient = new System.Net.WebClient();
    myWebClient.DownloadFile(source,fileName);
   }
   catch(Exception ex)
   {
    throw new Exception("下载失败，原因是：" + ex.Message,ex);
   }
  }

webservices如下:

[WebMethod(Description = "取得更新版本")]
    public string GetVer()
    {
        XmlDocument doc = new XmlDocument();
        doc.Load(Server.MapPath("update/update.xml"));
        XmlElement root = doc.DocumentElement;
        return root.SelectSingleNode("version").InnerText;
    }

    [WebMethod(Description = "在线更新软件")]
    public System.Xml.XmlDocument GetUpdateData()
    {
        //取得更新的xml模板内容
        XmlDocument doc = new XmlDocument();
        doc.Load(Server.MapPath("update/update.xml"));
        XmlElement root = doc.DocumentElement;
        //看看有几个文件需要更新
        XmlNode updateNode = root.SelectSingleNode("filelist");
        string path = updateNode.Attributes["sourcepath"].Value;
        int count = int.Parse(updateNode.Attributes["count"].Value);
        //将xml中的value用实际内容替换
        for (int i = 0; i < count; i++)
        {
            XmlNode itemNode = updateNode.ChildNodes[i];
            string fileName = path + itemNode.Attributes["name"].Value;
            FileStream fs = File.OpenRead(Server.MapPath(fileName));
            itemNode.Attributes["size"].Value = fs.Length.ToString();
            BinaryReader br = new BinaryReader(fs);
            //这里是文件的实际内容，使用了Base64String编码
            itemNode.SelectSingleNode("value").InnerText = Convert.ToBase64String(br.ReadBytes((int)fs.Length), 0, (int)fs.Length);
            br.Close();
            fs.Close();
        }
        return doc;
    }

再建一个xml
<?xml version="1.0" encoding="utf-8" ?>
<product>
  <version>1.0.1818.42821</version>
  <description>修正一些Bug</description>
  <filelist count="7" sourcepath="./update/">
    <item name="WinQp.exe" size="">
      <value />
    </item>
    <item name="AccessDAL.dll" size="">
      <value />
    </item>
    <item name="LocalBLL.dll" size="">
      <value />
    </item>
    <item name="Model.dll" size="">
      <value />
    </item>
    <item name="MyADO.dll" size="">
      <value />
    </item>
    <item name="Common.dll" size="">
      <value />
    </item>
    <item name="Excel.dll" size="">
      <value />
    </item>
  </filelist>
</product>
放在服务器上

再新建 一个升级程序,在主程序下调用这个程序,升级程序内容为
            if (!File.Exists(Application.StartupPath+"\\update.xml"))
            {
                MessageBox.Show("升级程序不能单独运行！");
                Application.Exit();
            }
            System.Diagnostics.Process[] ps = System.Diagnostics.Process.GetProcesses();
            foreach (System.Diagnostics.Process p in ps)
            {
                //MessageBox.Show(p.ProcessName.ToLower());
                if (p.ProcessName.ToLower() == "qpwin")
                {
                    if (!p.HasExited)
                    {
                        p.Kill();
                        p.WaitForExit();
                    }
                    break;
                }
            }
            XmlDocument doc = new XmlDocument();
            doc.Load(Application.StartupPath + @"\update.xml");
            XmlElement root = doc.DocumentElement;
            XmlNode updateNode = root.SelectSingleNode("filelist");
            string path = updateNode.Attributes["sourcepath"].Value;
            int count = int.Parse(updateNode.Attributes["count"].Value);
            for (int i = 0; i < count; i++)
            {
                XmlNode itemNode = updateNode.ChildNodes[i];
                string fileName = itemNode.Attributes["name"].Value;
                FileInfo fi = new FileInfo(fileName);
                fi.Delete();
                //File.Delete(Application.StartupPath + @"\" + fileName);
                this.label1.Text = "正在更新： " + fileName + " (" + itemNode.Attributes["size"].Value + ") ...";
                FileStream fs = File.Open(fileName, FileMode.Create, FileAccess.Write);
                fs.Write(System.Convert.FromBase64String(itemNode.SelectSingleNode("value").InnerText), 0, int.Parse(itemNode.Attributes["size"].Value));
                fs.Close();
            }
            label1.Text = "更新完成";
            File.Delete(Application.StartupPath + @"\update.xml");
            label1.Text = "正在重新启动应用程序...";
            System.Diagnostics.Process.Start("qpwin.exe");
            Close();
            Application.Exit();