Abstract: Capacity attenuation of power battery is a problem caused by excessively high discharge current during electric vehicle driving. Thus a fully active hybrid energy storage system composed of a lithium-ion power battery, a supercapacitor and multi-port DC/DC converter is constructed, where the current and voltage loop controllers are responsible for the controlling of output current and DC bus voltage, respectively. Then taking the supercapacitor SOC, vehicle demand power and vehicle speed as input variables, and lithium-ion power battery output power as the output variable, a fuzzy logic-based energy management strategy for an energy storage system is proposed by constructing 45 fuzzy rules. The charge and discharge power of the lithium-ion battery and supercapacitor are adjusted by the fuzzy logic controller, which ensures the peak power demand of the vehicle during starting and acceleration, and avoids the impact of high-frequency current fluctuations on the life attenuation of the power battery. When the power demand is low, the power battery charges the ultracapacitor. Experimental results under HWFET show that the proposed fully active dual-energy source hybrid energy storage system and the energy management strategy based on fuzzy logic can effectively protect lithium-ion power battery from large current fluctuations, thereby extending lithium-ion power battery life.