public static string Html2Text(string htmlStr)

{

    if (String.IsNullOrEmpty(htmlStr))

    {

        return "";

    }

    string regEx_style = "<style[^>]*?>[\\s\\S]*?<\\/style>"; //定义style的正则表达式 

    string regEx_script = "<script[^>]*?>[\\s\\S]*?<\\/script>"; //定义script的正则表达式   

    string regEx_html = "<[^>]+>"; //定义HTML标签的正则表达式   

    htmlStr = Regex.Replace(htmlStr, regEx_style, "");//删除css

    htmlStr = Regex.Replace(htmlStr, regEx_script, "");//删除js

    htmlStr = Regex.Replace(htmlStr, regEx_html, "");//删除html标记

    htmlStr = Regex.Replace(htmlStr, "\\s*|\t|\r|\n", "");//去除tab、空格、空行

    htmlStr = htmlStr.Replace(" ", "");

    htmlStr = htmlStr.Replace(""", "");//去除异常的引号" " "

    htmlStr = htmlStr.Replace(""", "");

    return htmlStr.Trim();

}

Html2Text