The invention discloses a battery supply system. The battery supply system is characterized by comprising a battery pile and a plurality of isolated DC/DC conversion units connected between the battery pile and a power output end of the system, wherein each isolated DC/DC conversion unit comprises a unit input power anode connected with the anode of the battery pile, a unit input power cathode connected with the cathode of the battery pile, a transformer primary coil, a power electronic switch, a primary control unit, a conversion output and bypass unit and a unit power output end. According to the battery supply system, the battery pile with low voltage and high current is converted into an isolated high-voltage power output system by using the isolated DC/DC conversion units, so that the problem that the requirement of load for battery voltage is met by serially connecting battery cells is solved.