我参照了这个，我要做的是把域里的NT账号拉出来，和本机做对比。
http://www.cnblogs.com/KingOfSoft/archive/2007/05/12/743693.html
获取域账号主要写了3个方法，但是取出来的是null

C# code

    protected void Page_Load(object sender, EventArgs e)
    {
        string[] NTUserList = GetOrganizationalUnit("LDAP://MyNT", "Administrator", "", "user");
    }
    private string[] GetOrganizationalUnit(string domainADsPath, string username, string password, string schemaClassNameToSearch)
    {
        SearchResultCollection results = _ADHelper(domainADsPath, username, password, schemaClassNameToSearch);
        string[] sRe = GetGetOrganizationalUnitResults(results);

        results.Dispose();

        return sRe;
    }

    private static SearchResultCollection _ADHelper(string domainADsPath, string username, string password, string schemaClassNameToSearch)
    {
        DirectorySearcher searcher = new DirectorySearcher();

        searcher.SearchRoot = new DirectoryEntry(domainADsPath,username, password);
        searcher.Filter = "(objectClass=" + schemaClassNameToSearch + ")";

        searcher.SearchScope = SearchScope.Subtree;
        searcher.Sort = new SortOption("name", System.DirectoryServices.SortDirection.Ascending);
        searcher.PageSize = 512;

        searcher.PropertiesToLoad.AddRange(new string[] { "name", "Path", "displayname", "samaccountname", "mail" });

        SearchResultCollection results = searcher.FindAll();
        return results;
    }

    private string[] GetGetOrganizationalUnitResults(SearchResultCollection results)
    {
        string sRe = string.Empty;
        if (results.Count == 0)
            throw new Exception("域中没有任何组织结构");
        else
        {
            foreach (SearchResult result in results)
            {
                if (result.Path.IndexOf("OU=用户") < 0)
                    continue;
                ResultPropertyCollection propColl = result.Properties;
                sRe += propColl["name"][0].ToString() + ',';
            }
        }
        if (sRe.Length > 0)
            sRe = sRe.Substring(0, sRe.Length - 1);
        return sRe.Split(',');
    }

还有就是_ADHelper（）方法里的password参数是指的哪个password？windows的？