百度有一个公开的歌词下载API，具体介绍可以去看看这位帅哥的日志http://blog.163.com/fengedkail/blog/static/586507602008101575730334/

using System;

using System.IO;

using System.Text;

using System.Text.RegularExpressions;

using System.Net;

  /// <summary>

  /// 歌词下载类

  /// </summary>

  class DownLoadGeCi

  {

  string urlSongInfor = "http://box.zhangmen.baidu.com/x?op=12&count=1&title={0}$${1}$$$$";//获取歌曲信息的地址

  string urlGeCi = "http://box.zhangmen.baidu.com/bdlrc/";//下载歌词的不完全地址

  /// <summary>

  /// 获取歌词

  /// <param name="songName">歌曲名称</param>

  /// <param name="singerName">演唱人</param>

  /// </summary>

  public string getSongWord(string songName,string singerName)

  {

  urlSongInfor = String.Format(urlSongInfor,songName,singerName);//url地址

  string content = getWebContent(urlSongInfor);//获取歌曲信息

  string matchCount = @"<count>(?<count>\d+)</count>";//匹配找到歌词个数的正则表达式

  string matchLrcid = @"<lrcid>(?<id>\d+)</lrcid>";//匹配歌词加密文件名的正则表达式

  int songCount = 0;//找到歌词个数

  int lrcid = 0;//歌词加密文件名

  Regex regex = new Regex(matchCount);

  Match songInfo= regex.Match(content);

  songCount=Convert.ToInt32(songInfo.Groups["count"].Value);

  if (songCount == 0)

  {

  return "没有找到歌词";//搜索到的歌词数为0

  }

  regex = new Regex(matchLrcid);  

  MatchCollection matchResult=regex.Matches(content);

  foreach (Match temp in matchResult)

  {

  lrcid = Convert.ToInt32(temp.Groups["id"].ToString());

  break;

  }

  int fileID = lrcid/ 100;//计算出加密后的歌词文件名

  urlGeCi += fileID + "/" + lrcid + ".lrc";

  return getWebContent(urlGeCi);

  }

  /// <summary>

  /// 获取远程网页内容

  /// </summary>

  /// <param name="url">url地址</param>

  /// <returns></returns>

  private string getWebContent(string url)

  {

  try

  {

  StringBuilder sb = new StringBuilder("");

  WebRequest request = WebRequest.Create(url);

  request.Timeout = 10000;//10秒请求超时

  StreamReader sr = new StreamReader(request.GetResponse().GetResponseStream(), Encoding.GetEncoding("GB2312"));

  while (sr.Peek() >= 0)

  {

  sb.Append(sr.ReadLine());

  }  

  return sb.ToString();

  }

  catch (WebException ex)

  {

  return ex.Message;

  }

    

  }

  }

示例调用：

DownLoadGeCi download = new DownLoadGeCi();

richTxtContent.Text= download.getSongWord("遇","aimini");