To solve problems like communication failure, data transmission error during the remote updating process of embedded devices. This article design and implement a remote update system with an improved security mechanism based on traditional application backup method. With the help of a simplified safe application which contains only core code of normal application, this System can remain stable during the time when updating process is held up due to data communication failure. The system uses multiverification mechanism and it uses differential data instead of updating the whole software, reducing information flow consumption and extend wipe/write operational life of FLASH. The test result proved the security and stability of the system during remote updating process.