在“Turtletreed”所说的帮助下，我成功地让它工作了。我的代码很好，只是需要更改两件事。我从中删除了自定义字段$user_data, 在后面加上这个wp_insert_user --

  add_user_meta($user_id, \'broker_email\', $b_email);

add_action(\'template_redirect\', \'register_a_user\');
function register_a_user(){
    if(isset($_GET[\'do\']) && $_GET[\'do\'] == \'register\'):
    $errors = array();
    if(empty($_POST[\'user\']) || empty($_POST[\'email\'])) $errors[] = \'provide a user and email\';
    if(!empty($_POST[\'spam\'])) $errors[] = \'gtfo spammer\';
    if(!empty($_POST[\'pass1\']) && !empty($_POST[\'pass2\'])) $error[] = \'The passwords you entered do not match\';

    $account = esc_attr($_POST[\'account_type\']);
    $user_login = esc_attr($_POST[\'user\']);
    $user_email = esc_attr($_POST[\'email\']);
    $user_pass = esc_attr($_POST[\'pass1\']);
    $user_pass2 = esc_attr($_POST[\'pass2\']);
    $user_first = $_POST[\'first_name\'];
    $user_last = $_POST[\'last_name\'];
    $b_email = $_POST[\'broker_email\'];

    require_once(ABSPATH.WPINC.\'/registration.php\');

    $sanitized_user_login = sanitize_user($user_login);
    $user_email = apply_filters(\'user_registration_email\', $user_email);

    if(!is_email($user_email)) $errors[] = \'invalid e-mail\';
    elseif(email_exists($user_email)) $errors[] = \'this email is already registered\';

    if(empty($sanitized_user_login) || !validate_username($user_login)) $errors[] = \'invalid user name\';
    elseif(username_exists($sanitized_user_login)) $errors[] = \'user name already exists\';

    if(empty($errors)):
    if ( $_POST[\'pass1\'] == $_POST[\'pass2\'] ) {

    $user_data = array (
        \'user_login\' => $sanitized_user_login,
        \'user_pass\' => $user_pass,     
        \'user_email\' => $user_email,
        \'user_first\' => $user_first,
        \'user_last\' => $user_last,
        \'role\' => $account
    );

    // Create the user
    $user_id = wp_insert_user( $user_data );
    add_user_meta($user_id, \'broker_email\', $b_email);
} else { 
$errors[] = \'passwords dont match\'; 
}
      if(!$user_id):
        $errors[] = \'registration failed...\';
      else:
        wp_new_user_notification($user_id);
      endif;
    endif;

    if(!empty($errors)) define(\'REGISTRATION_ERROR\', serialize($errors));
    else define(\'REGISTERED_A_USER\', $user_email);
  endif;
}

function auto_login_new_user( $user_id ) {
        wp_set_current_user($user_id);
        wp_set_auth_cookie($user_id);
            // You can change home_url() to the specific URL,such as 
        wp_redirect( \'http://YOURURL.COM\' );
    }
    add_action( \'user_register\', \'auto_login_new_user\' );