Energy management strategy of Wind-PV-Storage Microgrid during islanded operation is proposed in this paper. Based on the analysis of the structure and function of microgrid energy management, the coordination operation mode between lithium batteries and supercapacitors is elaborated in the strategy combined with the generation and demand side management. In hybrid storage device, batteries can smooth the system output according to operation plan which depends on the results of renewable energy power prediction and load forecast. And the supercapacitors are responsible for short term adjustment including real-time power balance and frequency control. The simulation results demonstrate that the energy management strategy can optimize the battery life, balance the instantaneous power and stabilize microgrid operation.