The present invention provides a battery management system, which is applicable to at least one battery string, wherein each battery string comprises a plurality of batteries connected in series. The battery management system comprises a plurality of battery sensors and a main controller. Each battery sensor measures at least one corresponding battery and has a first communication module, and each battery sensor issues a broadcast through the first communication module when its power is activated. The main controller has a second communication module. The second communication module and the first communication modules are signal connected in parallel. The main controller executes a web server program to provide a web page. When the main controller receives the broadcast, the main controller displays an addressing interface by the web page, so as to assign each battery sensor to at least one corresponding battery to complete the addressing of the battery sensors.