The power battery pack is the only power source for pure electric vehicles, the vehicle"s energy core. For electric vehicles that is running, the battery management system need to real-time monitor single batteries’ voltages of the battery pack, and in order to achieve balanced control between the battery cells. This article completes the acquisition board’s design of twelve battery voltages based on LTC6802, and achieves a balance control circuit within the battery pack. Test experiments demonstrated that the experimental board’s voltage acquisition accuracy can reach 99.5%, and the balance circuit can work fast and accurately.