magento重设block

<cms_index_index>
    <reference name="header">
        <action method="unsetChild"><name>logo</name></action>
        <block type="page/html_header" name="logo" as="logo" template="page/html/logo-home.phtml"/>
    </reference>
</cms_index_index>

先删除原先的block，再重新定义。