How to show Subcategory Alphabetically in Magento?

Just copy and paste in your page like list.phtml or home.phtml

<?php
$cats = Mage::getModel(‘catalog/category’)->load(51)->getChildren();
$catIds = explode(‘,’,$cats);

$categories = array();
foreach($catIds as $catId) {
$category = Mage::getModel(‘catalog/category’)->load($catId);
$categories[$category->getName()] = $category->getUrl();
}

ksort($categories, SORT_STRING);
?>

<ul>
<?php foreach($categories as $name => $url): ?>
<li>
<a href=”<?php echo $url; ?>”><?php echo $name; ?></a>
</li>
<?php endforeach; ?>
</ul>

Hope it will work