diffrent theme for admin without use theme appearance config by default Drupal(7) use "page.tpl.php" for all(front and admin) pages.but I want use another file for example "page-admin.tpl.php" for admin layout.i don't want change admin theme in config/appearance.
Copy page.tpl.php to page--admin.tpl.php (note two hyphens) clear theme registry / all caches and should be good to go.