$current_cat_id = get_queried_object_id();
$kids = get_terms([
    \'taxonomy\' => get_queried_object()->taxonomy,
    \'parent\'   => $current_cat_id,
]);

<?php

$terms = get_terms([
    \'taxonomy\' => get_queried_object()->taxonomy,
    \'parent\'   => get_queried_object_id(),
]);

echo \'<div style="height: 200px; text-transform: uppercase; border:1px solid #666666; padding:10px; overflow-y: scroll;">
<ul>
foreach ( $terms as $term) {
    echo \'<li><a href="\' . get_term_link( $term ) . \'">\' . $term->name . \'</a></li>\';  
}
echo \'</ul>
<br />\';

是否要列出所有子类别，即当前类别中的子类别？

如果是，那么您可以使用以下简单的代码片段，帮助您列出当前帖子父类别中的所有子类别。

Code for Getting subcategories of current category

<ul id="all-sub-categories">

<?php
   $postcat = get_the_category( $post->ID );
   foreach ($postcat as $cat) {
      if ($cat->parent != 0) {
        echo "<li><a href=\'" . get_category_link( $cat->term_id ) . "\'>" . $cat->name . "</a></li>";
      }
   }
?>

</ul>

终于找到了解决方法。。。在侧栏模板中添加以下代码。您可以用自定义分类法替换“类别”分类法。

<?php
        // get Post Object outside
        $queried_object = get_queried_object();
        if ( $queried_object ) {
            $post_id = $queried_object->ID;
        }
        //Returns All Term Items for "my_taxonomy"
        $term_list = wp_get_post_terms($post_id, \'category\', array("fields" => "all"));
        $term_list_id = wp_get_post_terms($post_id, \'category\', array("fields" => "ids"));
        echo \'<ul>\';
        foreach($term_list as $term) {
            $has_parent = $term->parent;
            $has_childrens = get_terms( $term->taxonomy, array( \'parent\'    => $term->term_id, \'hide_empty\' => false) );
            // If it have parents...
            if ( $has_parent ) {
                // If parent category is already selected
                if(in_array($has_parent, $term_list_id)){
                    // Do nothing
                }else{
                    // If parent category is not selected
                    $parent_id = $term->parent;
                    $parent_term = get_term( $parent_id, \'category\' );
                    // Display Parent
                    echo \'<li><a href="\' . get_category_link( $parent_id ) . \'">\' . $parent_term->name.\'</a></li>\';
                    echo \'<ul>\';
                    // Display Children
                    $childrens = get_categories( array(\'child_of\' => $parent_id), \'category\' );
                    foreach($childrens as $children) {
                        echo \'<li><a href="\' . get_category_link( $children->term_id ) . \'">\' . $children->name.\'</a></li>\';
                    }
                    echo \'</ul>\';
                }
            }elseif ( $has_childrens ) {
                // If it have childrens...
                // display parent
                echo \'<li><a href="\' . get_category_link( $term->term_id ) . \'">\' . $term->name.\'</a></li>\';
                    $childrens = get_categories( array(\'child_of\' => $parent_id), \'category\' );
                    echo \'<ul>\';
                // Display children
                foreach($has_childrens as $has_children) {
                    echo \'<li><a href="\' . get_category_link( $has_children->term_id ) . \'">\' . $has_children->name.\'</a></li>\';
                }
                echo \'</ul>\';
            }else{
                // No Parent No Child
                echo \'<li><a href="\' . get_category_link( $term->term_id ) . \'">\' . $term->name.\'</a></li>\';
            }
        }
        echo \'</ul>\';
    ?>