Power battery management system is a very important part in electric vehicle. Currently, power battery management system is only monitor and control of the power batteries group voltage. This may cause a single battery overcharge and over-discharge, thus affecting cycle life of the power battery. In this paper, for each cell in the batteries group is monitored and controlled to prevent any battery overcharge and over-discharge. Hardware and software of power battery management system has been designed. Experimental results show that power battery management system can accurately monitor the power batteries, thereby ensuring the safety of the power batteries and prolonging the cycle life of the power batteries group.