Embedded system firmware on-line upgrading system

The invention discloses an on-line upgrade method for embedded system firmware. A non-volatile memory is divided into two areas, the subareas to which a bootloader and a tiny_os belonging are protected, and an upgrade script is operated under the tiny_os to realize upgrading; the corresponding download request is provided by busybox of an open source; the support to a file system, a tcp/ip protocol stack and the like is provided by the tiny_os; the corresponding download request adopts dynamic linking technology and is shared with system software; different parameters are transmitted to a kernel through the bootloader, so as to tell upgrade operation from normal operation; and the entire upgrade system is only required to enlarge a storage space of about 400K, a plurality of download protocols and file systems can be supported. The invention further provides a spare upgrade method, so that when the subarea of the system software is damaged accidentally, the system upgrading also can be carried out, and the reliability and the safety of upgrading are ensured.