using System.DirectoryServices;

    /// <summary>

    /// AD账号登陆验证

    /// </summary>

    /// <param name="UserName">AD用户名</param>

    /// <param name="PassWord">AD密码</param>

    /// <param name="strOU">active directory 中的组织单位</param>

    /// <returns></returns>

    public bool Login(string UserName, string PassWord, string strOU)

    {

        String strPath = string.Format("LDAP://OU={0},OU=ZYE,DC=zhanyun,DC=com,DC=cn", strOU);

        DirectoryEntry AD = new DirectoryEntry(strPath);

        AD.Username = "zhanyun" + @"\" + UserName;

        AD.Password = PassWord;

        try

        {

            DirectorySearcher searcher = new DirectorySearcher(AD);

            searcher.Filter = String.Format("(sAMAccountName={0})", UserName);

            System.DirectoryServices.SearchResult result = searcher.FindOne();

            if (result == null)

            {

                return false;

            }

            AD.Close();

        }

        catch

        {

            return false;

        }

        finally

        {

            AD.Close();

        }

        return true;

    }

bool result = Login(username, password, "MIS");