The invention discloses a control method of a storage battery energy supply system. The storage battery energy supply system comprises a power supply circuit connected to a traction motor, a pluralityof storage batteries and a controller; each of the storage batteries is connected to the power supply circuit through a DC/DC converter. The control method comprises the following steps: the controller is used for optimizing storage battery power supply combination according to total power demand of the traction motor and a corresponding relationship between the power of each DC/DC converter andconversion efficiency, and the conversion efficiency of the energy supply system can be improved. In the storage battery energy supply system disclosed in the present invention, each storage battery is cascaded with a bidirectional DC/DC converter, and a plurality of bidirectional DC/DC outputs are connected in parallel and uniformly output to a direct current bus. When the system operates at lowpower, one or more groups of storage batteries can be turned off, the conversion efficiency of remaining working storage batteries can be improved, the efficiency of the entire system can be improved,and energy can be saved.