string str = "http://www.rczjp.cn/A/B/C/index.aspx?cid=11&sid=22";             Regex reg = new Regex(@"(?imn)(?
     
      http://[^/]+/)(?
      
       ([^/]+/)*([^/.]*$)?)((?
       
        [^?.]+\.[^?]+)\?)?(?
        
         .*$)");            MatchCollection mc = reg.Matches(str);            foreach (Match m in mc)            {                Console.WriteLine(m.Groups["do"].Value);  //http://www.rczjp.cn/                Console.WriteLine(m.Groups["dir"].Value); //A/B/C/                Console.WriteLine(m.Groups["page"].Value);  //index.aspx                Console.WriteLine(m.Groups["par"].Value); //cid=11&sid=22            }            Console.Read();