1.创建新模块 app/etc/Maker_Overridecontroller.xml 

<?xml version="1.0"?>
<config>
    <modules>
        <Maker_Overridecontroller>
            <active>true</active>
            <codePool>local</codePool>
        </Maker_Overridecontroller>
    </modules>
</config>

2. 创建 app/code/local/Maker/Overridecontroller/etc/config.xml

<?xml version="1.0"?>
<config>
    <modules>
        <Maker_Overridecontroller>
            <version>0.0.1</version>
        </Maker_Overridecontroller>
    </modules>
    <admin>
        <routers>
            <adminhtml>
                <args>
                    <modules>
                        <Maker_Overridecontroller before="Mage_Adminhtml">Maker_Overridecontroller</Maker_Overridecontroller>
                    </modules>
                </args>
            </adminhtml>
        </routers>
    </admin>
</config>

3. 创建控制器 
app/code/local/Justwebdevelopment/Overridecontroller/controllers/Catalog/ProductController.php

<?php
/**
 * Created by PhpStorm.
 * User: lollicup
 * Date: 2019/7/18
 * Time: 18:03
 */

include_once("Mage/Adminhtml/controllers/Catalog/ProductController.php");
class Maker_Overridecontroller_Catalog_ProductController extends Mage_Adminhtml_Catalog_ProductController
{
    public function editAction(){
        echo "Override Product Edit Action...";
        exit;
    }
}

然后清理缓存，运行后台