A low-temperature heating system and method for an electric vehicle battery based on hydraulic energy storage, including a generator, a hydraulic pump, a hydraulic motor, a transmission belt, a clutch, a DC / DC converter, a heating film, a battery pack, a one-way valve I, and a one-way valve Ⅱ. Energy storage control valve, heating control valve, overflow valve, accumulator group, pressure relay, controller and temperature sensor. The system utilizes a hydraulic energy storage device and regenerative braking energy to achieve rapid heating of the power battery when the electric vehicle starts at low temperature without an external heating source. This method is simple and reliable, and is easy to integrate with other heating methods, which can make up for the problem that battery self-heating is difficult to implement at a lower state of charge, thereby effectively solving the problem of large battery performance degradation and large battery performance when the electric steam is started under low temperature and severe cold conditions. The problem of poor work performance.