1、template.php

/**

 * Implements hook_theme().

 */

function yourtheme_theme($existing, $type, $theme, $path) {

  $base = array(

    'render element' => 'form',

    'path' => drupal_get_path('theme', 'yourtheme') . '/templates/forms',

  );

  return array(

    'commerce_checkout_form_checkout' => $base + array(

      'template' => 'commerce-checkout-form-checkout',

    ),

  );

}

/**

 * Preprocessor for commerce_checkout_form_checkout theme.

 */

function yourtheme_preprocess_commerce_checkout_form_checkout(&$variables) {

  /* Add or modify your variables */

}

2、/templates/forms/commerce-checkout-form-checkout.tpl.php

// Render or hide parts of $form: var_export($form);

// Example given:

hide($form['title']);

print render($form['first']);

// Render remaining form elements as usual.

print drupal_render_children($form);