In order to improve the energy utilization rate of electric hydraulic excavator and reduce the fluctuation of power supply,this paper focuses on the power system of variable speed electric hydraulic excavator using non-isolated bidirectional DC/DC converter and super capacitor group.In SimulationX,the model of half-bridge converter and supercapacitor energy storage system based on equivalent resistance was established by using full ripple modeling method.The parameters of each component and its controller were designed,and the adaptive control method was proposed.During simulation process,motor power fluctuation was simulated by variable speed signal and torque signal set by servo motor,so that the energy storage system of the bidirectional DC/DC converter automatically compensated or absorbed the power of power supply.The simulation results show that the proposed controller maintains a constant output power under the premise of ensuring the power of motor and the efficiency of supercapacitor,ensuring a fast dynamic response and reducing power fluctuations during switching process.