Abstract: The method of DC voltage supported by batteries is difficulty to meet the installed power increasing of wave energy converter（WEC）. A grid connection method for multi hydraulic power generation set（HPGS）based on inverter in DC voltage mode is proposed.The DC voltage is supported by inverter for multi HPGSs,and DC nano grid without batteries is established in WEC. The topology of DC voltage mode of inverter and the control strategy of DC voltage outer feedback loop are established. Through the computer simulation test of multi HPGS based on inverter DC voltage mode,the feasibility of grid connection method of multi HPGS without batteries is verified.The research results have been applied to the 500 kW“Chang Shan Hao”WEC,which lays a foundation for the grid connection system of high power WEC.