将下面代码添加到主题的functions.php即可
add_filter( 'post_thumbnail_html', 'remove_width_attribute', 10 );
add_filter( 'image_send_to_editor', 'remove_width_attribute', 10 );
function remove_width_attribute( $html ) {
$html = preg_replace( '/(width|height)="\\d*"\\s/', "", $html );
return $html;
}
