使用类、类的方法或类的属性都可以向线程传递参数：
public class UrlDownloader
{
    string url;

    public UrlDownloader (string url)
    {
        this.url = url;
    }

    public void Download()
    {
        WebClient wc = new WebClient();
        Console.WriteLine("Downloading " + url);                        
        byte[] buffer = wc.DownloadData (url);
        string download = Encoding.ASCII.GetString(buffer);
        Console.WriteLine(download);
        Console.WriteLine("Download successful.");

        //这里你可以将download进行保存等处理......
    }
}

[... 在另一个类中使用它们...]
              
UrlDownloader downloader = new UrlDownloader (yourUrl);
new Thread (new ThreadStart (downloader.Download)).Start();

注意参数是如何传递的。

在.NET 2.0中还可以这样：

(CODE-BESIDE）
方式一：

ThreadStart starter = delegate { Download(yourUrl); });
new Thread(starter).Start();
//使用线程池
WaitCallback callback = delegate (object state) { Download ((string)state); };
ThreadPool.QueueUserWorkItem (callback, yourUrl);

方式二(使用ParameterizedThreadStart)：
Thread t = new Thread (new ParameterizedThreadStart(DownloadUrl));
t.Start (myUrl);

static void DownloadUrl(object url)
{
    // ....
}