使用条件语句，例如：

$sub_cats = get_categories(\'parent=\'.get_query_var(\'cat\'));
if( $sub_cats ) : 
//show list of child categories, for instance with wp_list_categories()
 echo \'<ul>;
 wp_list_categories(\'title_li=&child_of=\'.get_query_var(\'cat\'));
 echo \'</ul>\';
//or possibly using $sub_cats and a foreach loop//
 echo \'<ul>\';
 foreach( $sub_cats as $sub_cat ) {
   echo \'<li><a href="\'.get_category_link($sub_cat->term_id).\'">\'.$sub_cat->name.\'</a></li>\'; 
  }
 echo \'</ul>\';
else:
//the \'normal\' LOOP of category.php//
endif;

编辑：添加子类别的列表代码