Гульназ

$terms_array = array( 
  'taxonomy' => 'services', // you can change it according to your taxonomy
  'parent'   => 0 // If parent => 0 is passed, only top-level terms will be returned
);
$services_terms = get_terms($terms_array); 
foreach($services_terms as $service): ?>
<h4><?php echo $service->name; ?></h4>
<?php 
$post_args = array(
      'posts_per_page' => -1,
      'post_type' => 'service', // you can change it according to your custom post type
      'tax_query' => array(
          array(
              'taxonomy' => 'services', // you can change it according to your taxonomy
              'field' => 'term_id', // this can be 'term_id', 'slug' & 'name'
              'terms' => $service->term_id,
          )
      )
);
$myposts = get_posts($post_args); ?>
<ul>
<?php foreach ( $myposts as $post ) : setup_postdata( $post ); ?>
  <li>
    <a href="<?php the_permalink(); ?>"><?php the_title(); ?></a>
  </li>
<?php endforeach; // Term Post foreach ?>
</ul>
<?php wp_reset_postdata(); ?>

<?php endforeach; // End Term foreach; ?>