thanks for reply, i already solve it myself. here is my code this only work for two level categories.
<?php
//get all categories then display all posts in each term
$taxonomy = 'category'; //change this name if you have taxonomy
$param_type = 'category__in';
$term_args=array(
'orderby' => 'name',
'order' => 'ASC'
);
$terms = get_terms($taxonomy,$term_args);
if ($terms) {
foreach($terms as $term){ //this foreach is for top level
if($term->parent == 0){
echo '<h2>'.$term->name.'</h2>'; //get top level category name
$term_args=array(
'orderby' => 'name',
'order' => 'ASC',
'child_of' => $term->term_id
);
$termss = get_terms($taxonomy,$term_args);
foreach( $termss as $terms ) { //this foreach is for second level
$args=array(
"$param_type" => array($terms->term_id),
'post_type' => 'post',
'post_status' => 'publish',
'posts_per_page' => -1,
'caller_get_posts'=> 1
);
$my_query = null;
$my_query = new WP_Query($args);
if( $my_query->have_posts() ) { ?>
<div class="category section">
<h3><?php echo 'Category '.$terms->name; //get second level category name?></h3>
<ul>
<?php
while ($my_query->have_posts()) : $my_query->the_post(); ?>
<li><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_title(); //get posts title name?></a></li>
<?php
endwhile;
?>
</ul>
</div>
<?php
}}
}
}
}
wp_reset_query(); // Restore global post data stomped by the_post().
?>