Abstract: For reducing the fluctuation of renewable energy output power in maximum degree and optimizing the operation of hybrid energy storage system（HESS）,this paper adopted the low-pass filtering algorithm whose time constant was mixed with the state of charge（SOC） of HESS to determine the goal output,and adopted the fuzzy control theory to distribute the power deviation out of the leveling target between two energy storage mediums,according to the SOCs of batteries and supercapacitors.For reducing the number of times of battery charging and discharging,the supercapacitors compensate the power deviation independently when their energy was adequate.Numerical results showed that the control strategy could effectively level the fluctuation of renewable energy power,avoid the out-of-limit phenomenon of energy storage mediums,and achieve the purpose for prolonging batteries’ life.