看了篇文章可能会用的上，直接贴过来了。
private bool UrlIsExist(String url) { System.Uri u = null; try { u = new Uri(url); } catch { return false; } bool isExist = false; System.Net.HttpWebRequest r = System.Net.HttpWebRequest.Create(u) as System.Net.HttpWebRequest; r.Method = "HEAD"; try { System.Net.HttpWebResponse s = r.GetResponse() as System.Net.HttpWebResponse; if (s.StatusCode == System.Net.HttpStatusCode.OK) { isExist = true; } } catch (System.Net.WebException x) { try { isExist = ((x.Response as System.Net.HttpWebResponse).StatusCode != System.Net.HttpStatusCode.NotFound); } catch { isExist = (x.Status == System.Net.WebExceptionStatus.Success); } } return isExist; } protected void Page_Load(object sender, EventArgs e) { Response.Write("<li>http://dotnet.aspx.cc/Images/ 是否存在：" + UrlIsExist("http://dotnet.aspx.cc/Images/")); Response.Write("<li>http://dotnet.aspx.cc/ImagesX/ 是否存在：" + UrlIsExist("http://dotnet.aspx.cc/ImagesX/")); Response.Write("<li>http://xxxxx/ 是否存在：" + UrlIsExist("http://xxxxx/")); Response.Write("<li>hxxxxxxxxxxxxxxxxxxx 是否存在：" + UrlIsExist("hxxxxxxxxxxxxxxxxxxx")); Response.Write("<li>http://dotnet.aspx.cc/Images/logoSite.gif 是否存在：" + UrlIsExist("http://dotnet.aspx.cc/Images/logoSite.gif")); Response.Write("<li>http://dotnet.aspx.cc/Images/logoSite2.gif 是否存在：" + UrlIsExist("http://dotnet.aspx.cc/Images/logoSite2.gif")); } 
