The invention discloses a battery management system which comprises a plurality of battery module monitoring units, a master control unit and an equalization module. The maser control unit performs the functions of receiving data information which is transmitted from the battery module monitoring units, communicating with an electric vehicle whole-vehicle control unit and a charger, detecting a total voltage, a total current and an insulativity, estimating the charge state and health state of the battery according to the acquired battery data, and protecting charging and discharging of the battery. The battery management system realizes battery data acquisition, state estimation, equalization management and charging/discharging protection. The voltage, the current and the battery temperature of a lithium battery are measured. Charging or discharging is controlled according to the current state of the lithium battery, thereby preventing overcharging and over-discharging, and ensuring high safety of the lithium battery and the electric vehicle.