使用custom query for this.

$user_id = 1;
$the_query = new WP_Query( array( \'post_type\' => \'attachment\', \'post_status\' => \'inherit\', \'author\' => $user_id) );
if ( $the_query->have_posts() ) while ( $the_query->have_posts() ) : $the_query->the_post();
   the_title();
endwhile;