Abstract: Aiming at the performance differences of battery monomer or the differences after repeated charge and discharge, a simple and efficient equalization circuit including inductances,diodes and switching devices is designed for series connected batteries, and equalization repeated charge and discharge of battery is achieved. The article analyzes the principle of the equalization circuit, realizes the equalization of electric power by using the voltage and state which are input into DSP to generate PWM for controlling switching devices. The effect of experiment is obvious.