これを試してみてください。
require_once'app / Mage.php'; Mage :: app('default'); /*デフォルトまたはストアビュー名。* /
/* get a new category object */
$category = Mage::getModel('catalog/category');
$category->setStoreId(0); /* 0 = default/all store view. If you want to save data for a specific store view, replace 0 by Mage::app()->getStore()->getId(). */
$general['name'] = "My Category";
$general['path'] = "1/2/23"; /* catalog path */
$general['description'] = "Great My Category";
$general['meta_title'] = "My Category"; /* Page title */
$general['meta_keywords'] = "My , Category";
$general['meta_description'] = "Some description to be found by meta search robots. 2";
$general['landing_page'] = ""; /* has to be created in advance, here comes id */
$general['display_mode'] = "PRODUCTS_AND_PAGE"; /* static block and the products are shown on the page */
$general['is_active'] = 1;
$general['is_anchor'] = 0;
$general['page_layout'] = 'two_columns_left';
/* $general['url_key'] = "cars";//url to be used for this category's page by magento. */
/* $general['image'] = "cars.jpg"; */
$category->addData($general);
try {
$category->save();
echo "Success! Id: " . $category->getId();
} catch (Exception $e) {
echo $e->getMessage();
}