Because of the uncertainties and significant fluctuations of both power generation and consumption in a microgrid， the lead-acid battery energy storage system（BESS） endures too large fluctuations in battery charge and discharge currents to maintain the battery lifetime. This paper presents a hybrid energy storage system composed of super-capacitors and batteries. The mathematical model is given and its small signal stability criteria is also derived. Based on the topology of the hybrid energy storage system， the multi-hysteresis control strategy is adopted to improve the flexibility and practicability of the energy storage. Comparing the hybrid energy storage system with the BESS， it can be concluded that because of the high power density of the super-capacitor and the optimized control of the bi-directional DC/DC converter， some advantages can be attained. These include higher capacity usage rate and reduction of maintenance interruptions and operation costs. Both the simulation and experimental results verify the excellent performance of the proposed hybrid energy storage system.