Display sub-categories on category page

First create a new phtml file and save it in your/app/design/frontend/default/yourTheme/template/catalog/category folder.

1-     we have to find the category id for the page we're looking at. (This code will only be called when we're on a category page). We find the id with the following code:

//get the current category

$_cat = new Mage_Catalog_Block_Navigation();

$currentCat = $_cat->getCurrentCategory();

              

2-    This gives us the current category, in the next step we'll use its id to find the sub categories (children) associated with it.

//get the children of the current category

$subCats = Mage::getModel('catalog/category')

              ->load($currentCat->getId())->getChildren();

                              

                              

3-    $subCats now contains a comma separated list of the ids of the sub categories. We need to get rid of the commas:

//get sub category ids

$subCatIds = explode(',',$subCats);

                              

4-    Now the last step is-

<?php if (count($subCatIds) > 1): ?>

 <ul>

  <?php foreach($subCatIds as $subCatId): ?>

   <?php $subCat = Mage::getModel('catalog/category')->load($subCatId); ?>

               <?php if($subCat->getIsActive()): ?>

                <li>

      <?php //display category image

                 if($subCat->getImageUrl()): ?>

                  <img src="<?php echo $subCat->getImageUrl(); ?>" />

                 <?php endif; ?>

                 <a href="<?php echo $subCat->getUrl(); ?>">

                 <?php echo $subCat->getName(); ?>

                 </a>

                </li>

               <?php endif; ?>

   <?php endforeach; ?>

  </ul>

<?php endif; ?>