using System.Text.RegularExPRessions;//需要引用

  // 利用正則表達式去掉"<"和">"之間的內容
  private string StripHT(string strHtml)
  {
   Regex regex=new Regex("<.+?>",RegexOptions.IgnoreCase);
   string strOutput=regex.Replace(strHtml,"");
   return strOutput;
  }

//方法二(不知為什么此方法占用CPU100%)

public static string DropHTML(string strHtml)
  {
   string [] aryReg ={
          @"<script[^>]*?>.*?</script>",
          @"<(///s*)?!?((/w+:)?/w+)(/w+(/s*=?/s*(([""''])(//[""''tbnr]|[^/7])*?/7|/w+)|.{0})|/s)*?(///s*)?>",
          @"([/r])[/s]+",
          @"&(quot|#34);",
          @"&(amp|#38);",
          @"&(lt|#60);",
          @"&(gt|#62);",
          @"&(nbsp|#160);",
          @"&(iexcl|#161);",
          @"&(cent|#162);",
          @"&(pound|#163);",
          @"&(copy|#169);",
          @"&#(/d+);",
          @"-->",
          @"<!--.*"        
         };

   string [] aryRep = {
           "",
           "",
           "",
           "/"",
           "&",
           "<",
           ">",
           " ",
           "/xa1",//chr(161),
           "/xa2",//chr(162),
           "/xa3",//chr(163),
           "/xa9",//chr(169),
           "",
           "/r",
           ""   
          };

   string newReg =aryReg[0];
   string strOutput=strHtml;
   for(int i = 0;i<aryReg.Length;i++)
   {
    Regex regex = new Regex(aryReg[i],RegexOptions.IgnoreCase );
    strOutput = regex.Replace(strOutput,aryRep[i]);
   }

   strOutput.Replace("<","");
   strOutput.Replace(">","");
   strOutput.Replace("/r","");
   return strOutput;
     
  }
http://www.survivalescaperooms.com/wang123/archive/2006/09/16/505758.html