使用循环的嵌套来实现WordPress调用指定ID父分类下的子分类，二、三级分类都可以实现。代码如下：

<?php
$args=array(
'child_of'=> '666',
'hide_empty'=>'0',
);
$categories=get_categories($args);
foreach($categories as $category) {?>
 
<h5 class="title"><a href="<?php echo get_category_link( $category->term_id ) ;?>" title="' . $category->name.'"><?php echo $category->name;?></a></h5>
<ul>
<?php
$argszifenlei=array(
'child_of'=> $category->term_id,
'hide_empty'=>'0',
);
$categorieszifenlei=get_categories($argszifenlei);
foreach($categorieszifenlei as $categoryzifenlei) {
echo '<li ><a href="' . get_category_link( $categoryzifenlei->term_id ) . '" title="' . sprintf( __( "View all posts in %s" ), $categoryzifenlei->name ) . '" ' . '>' . $categoryzifenlei->name.'</a></li>';
}
?>
</ul>';
<?php }
?>

在任意位置都可以实现，指定ID父分类调用子分类名称

<?php
$categories=get_categories("child_of=666");
  foreach($categories as $category) {
	echo '<li class="wodepress"><a href="'.get_category_link( $category->term_id ).'">'.$category->name.'</a></li>';
  }
?>

子分类使用父分类模板

 function f_category_template($template){
	$category = get_queried_object();
	if($category->parent !='0'){
		while($category->parent !='0'){
			$category = get_category($category->parent);
		}
	}
	
	$templates = array();
 
	if ( $category ) {
		$templates[] = "category-{$category->slug}.php";
		$templates[] = "category-{$category->term_id}.php";
	}
	$templates[] = 'category.php';
	return locate_template( $templates );
}

category和archives调用下级子分类的名称和链接

<?php if ( is_category() ) { $this_category=g et_category( $cat ); } ?>
<?php if ( $this_category->category_parent ) 
$this_category = wp_list_categories( 'orderby=id&show_count=0&title_li=&use_desc_for_title=1&child_of='.$this_category->category_parent."&echo=0" ); 
else $this_category = wp_list_categories( 'orderby=id&depth=1&show_count=0&title_li=&use_desc_for_title=1&child_of='.$this_category->cat_ID."&echo=0" ); 
if ( $this_category ) { ?>
<ul>
<?php echo $this_category; ?>
</ul>
<?php } ?>

在制作wordpress列表模板的时候，经常会用到调用同录分类目录的情况，这段代码完美解决了这一问题。

<?php
$cat = get_queried_object();
$list = wp_list_categories( [
    'taxonomy' => $cat->taxonomy,
    'child_of' => $cat->parent,
    'title_li' => '',
    'echo'     => 0,
] );
if ( $list ) {
    echo "<ul>$list</ul>";
}
?>

专为导航而生，在wordpress模板制作过程中常常会在做breadcrumbs导航时会用到，子分类调用父分类的名称和链接，下面这段简洁的代码，可以完美解决这个问题。

<?php echo get_category_parents( $cat, true, ' &raquo; ' ); ?>

下面这种方法也可以，不过代码不够简洁。

<?php
if ( is_category() ) {
    // Get the current category term id.
    $query_obj = get_queried_object();
    $term_id   = $query_obj->term_id;
 
    echo get_term_parents_list( $term_id, 'category' );
}
?>

第三种方法，调用分类目录名称和链接，作为导航。

<?php
if ( ( is_tax() || is_category() || is_tag() ) ) {
    $trail     = '';
    $home      = '/<a href="' . get_home_url() . '">Home</a>';
    $query_obj = get_queried_object();
    $term_id   = $query_obj->term_id;
    $taxonomy  = get_taxonomy( $query_obj->taxonomy );
 
    if ( $term_id && $taxonomy ) {
        // Add taxonomy label name to the trail.
       // $trail .=  '/' . $taxonomy->labels->menu_name;
        // Add term parents to the trail.
        $trail .= '/' . get_term_parents_list( $term_id, $taxonomy->name, array( 'inclusive' => false ) );
    }
 
    // Print trail and add current term name at the end.
    echo '<p class="breadcrumb-trail">' . $home . $trail . $query_obj->name . '</p>';
}
?>