首先创建新列：

add_filter( \'manage_edit-post_columns\', \'c3m_new_column\');
function c3m_new_column( $defaults ) {
    $dfaults[\'post_thumbnail\'] = \'Post Thumbnail\';
    return $defaults;
}

add_action( \'manage_posts_custom_column\', \'c3m_custom_column\', 10, 2);
function c3m_custom_column( $column_name, $post_id ) {
    if ($column_name == \'post_thumbnail\') {
        if ( has_post_thumbnail() ) {
            $img_url = wp_get_attachment_image_src( get_post_thumbnail_id() );
            echo \'<img src="\'. esc_url( $img_url[0] ).\'" />\';
        } else { echo \'No Post Thumbnail Set\'; }
    }