您应该使用meta_key_num 而不是meta_key_number, 因此get\\u posts的参数如下所示:
<?php
$post_list_args = array(
\'numberposts\' => 15,
\'order\' => \'DESC\',
\'orderby\' => \'meta_key_num\',
\'meta_key\' => \'sorting\',
\'tag\' => get_post_meta($post->ID, \'Tag\', true),
);
$post_list = get_posts( $post_list_args );
foreach ( $post_list as $post ) :
setup_postdata( $post );
?>