Currently the common online upgrade scheme of system software is not safety in network terminal devices, because if power outages happened or the terminal is restarted when the content of system software is erased, system software is damaged. It is not friendly to users, and requires restart system before and after upgrade system. In this paper, a new effective online upgrade scheme is proposed by controlling the key point status of upgrade process. And the approached method does not need to restart the devices before and after online upgrade, is not visible for users. It greatly improves users' friendly experience of users and is more safety than common upgrade scheme. The method is very suitable to requirements of upgrade for embedded network terminal device. The new upgrade method is verified by bed extension, doctor extension and doorway extension of health-care systems, is highly demanded to be safety and friendly to users, the results proved the correctness and reliability of the scheme.