In view of such flaws as short cycle life, high voltage fluctuation and low power density found in traditional battery energy storage system in micro-grid, a hybrid energy storage system, which is composed of battery and supercapacitor, as well as its control method, has thus been proposed. By making full use of the advantages of the two kinds of energy storage elements, a voltage equalization control of each battery and supercapacitor unit can be achieved with voltage equalization control, power control and V/f control strategies combined. Finally, the system is to be simulated by establishing a Matlab/Simulink model. The results show that the method helps to reduce the current fluctuation of storage battery and the voltage fluctuation of DC bus with the fluctuation of the load of power grid, thus verifying the feasibility of the adopted method.