The present invention relates to a rapid low-temperature self-heating method and device for a battery. Active controllable large-current lossless short-circuit self-heating cooperates with an external heater to implement rapid composite heating, so that a battery is rapidly heated in a low-temperature environment and is controlled to fall within an optimal working temperature interval, so as to improve energy utilization of the battery and durability of a battery system. Before the battery system is started, battery temperature is first determined; when the temperature is less than a threshold, an external short-circuit is first proactively triggered to generate a large current to implement self-heating inside the battery. The method is simple, easy to implement, and safe and reliable, and can effectively resolve a problem that an electric vehicle has large capacity degradation and poor working performance in a low-temperature severe cold working condition.