这里现有的答案很好，但不幸的是，由于答案的年龄，它不适用于WordPress的新版本。

下面的代码有两种改进：

1-这是WordPress新版本的推荐/最佳实践方法，自version 2.8

2-它允许您通过仪表板小部件界面选择分类法，而不是硬编码。

add_action( \'widgets_init\', \'custom_register_plugin_widget\' );

function custom_register_plugin_widget() {
    register_widget( \'Widget_Custom_Tax_Tag_Cloud\' );
}

/**
 * New "best practice" is to extend the built-in WP_Widget class
 *
 * Class Widget_Custom_tax_tag_cloud
 */
class Widget_Custom_Tax_Tag_Cloud extends WP_Widget {
    function __construct() {
        parent::__construct( \'custom_tax_tag_cloud\', \'Custom Taxonomy Tag Cloud\', array( \'description\' => \'Display a tag cloud for a custom taxonomy.\' ) );
    }

    /**
     * Allows for manipulation, calculation, etc. when saving the widget instance in the dashboard.
     *
     * @param array $new_instance
     * @param array $old_instance
     *
     * @return array
     */
    function update( $new_instance, $old_instance ) {
        return $new_instance;
    }

    /**
     * Echos the widget contents in a sidebar
     *
     * @param array $args - the general widget arguments
     * @param array $instance - the settings for this specific widget
     */
    function widget( $args, $instance ) {
        echo $args[\'before_widget\'];
        echo $args[\'before_title\'] . \'Your widget title\' . $args[\'after_title\'];
        $cloud_args = array( \'taxonomy\' => \'catalogtag\' );
        wp_tag_cloud( $cloud_args );
        echo $args[\'after_widget\'];
    }

    /**
     * Render the "Controls" in the dashboard menu under Appearance => Widgets
     *
     * @param array $instance - the settings for this instance of the widget
     *
     * @return null
     */
    function form( $instance ) {
        $instance = wp_parse_args( (array) $instance, array( \'title\' => \'\', \'taxonomy\' => \'post_tag\' ) );

        // Load the list of taxonomies available
        $taxonomies = get_taxonomies( array( \'public\' => TRUE , \'show_tagcloud\' => TRUE), \'objects\' );

        echo \'<p><label>Title</label><input name="\' . $this->get_field_name( \'title\' ) . \'" id="\' . $this->get_field_id( \'title\' ) . \'" value="\' . esc_attr( $instance[\'title\'] ) . \'" /></p>\';
        echo \'<p><label>Taxonomy</label><select name="\' . $this->get_field_name(\'taxonomy\') . \' id="\' . $this->get_field_id(\'taxonomy\') . \'">\';
        echo \'<option value="">Select Taxonomy...</option>\';
        foreach($taxonomies AS $tax) {
            echo \'<option value="\' . $tax->name . \'"\';
            echo ($tax->name == $instance[\'taxonomy\']) ? \' selected\' : \'\';
            echo \'>\';
            echo ( ! empty($tax->labels->singular_name)) ? $tax->labels->singular_name : $tax->label;
            echo \'</option>\';
        }
        echo \'</select></p>\';
    }
}