The present application discloses a wake-up method and wake-up system for a battery management system. The method may include converting, by a conversion unit, a low-voltage power signal detected at a low-voltage input port into a high-voltage wake-up signal, and receiving, by a high-voltage control module, a working voltage provided by a power battery pack under control of the high-voltage wake-up signal; controlling, by the high-voltage control module, the high-voltage transmission module to be turned on, providing the working voltage to a synchronous rectifying module by the turned-on high-voltage transmission module, and converting high-voltage electric energy provided by the power battery pack into low-voltage electric energy; and transmitting, under control of the synchronous rectifying module, the low-voltage electric energy to the low-voltage controller, and waking up the battery management system by the low-voltage controller.