WP_Query doesn’t works inside loop
try like this: if ($obj->have_posts()){ while($obj->have_posts()){ $obj->the_post(); $slug = get_the_tags(); $obj->the_title(); echo “<br/>”; $queryH = array(“cat”=>13,”order”=>”ASC”,”posts_per_page”=>-1,”tag__in”=>$slug); $objH = new WP_Query($queryH); if ($objH->have_posts()){ while($objH->have_posts()){ $objH->the_post(); $objH->the_title(); echo “<br/>”; } } } }