如果有人需要的话

$args = array(
    \'type\'                     => \'product\',
    \'parent\'                   => get_queried_object_id(),
    \'orderby\'                  => \'term_group\',
    \'hide_empty\'               => true,
    \'hierarchical\'             => 1,
    \'taxonomy\'                 => \'product_cat\',
    \'pad_counts\'               => false
);

$cats = get_categories( $args );
print_r(count($cats));