您可以使用get_query_var( \'term\' ) 获取当前术语和get_query_var( \'taxonomy\' ) to get the current taxonomy, then all that is left is to use [wp_dropdown_categories()][1] function with的子项parameter andtaxonomy参数，如下所示：

//first get the current term
 $current_term = get_term_by( \'slug\', get_query_var( \'term\' ), get_query_var( \'taxonomy\' ) );
//then set the args for wp_dropdown_categories
 $args = array(
    \'child_of\' => $current_term->term_id,
    \'taxonomy\' => $current_term->taxonomy,
    ); 
 wp_dropdown_categories( $args );