Aiming at the problem of energy loss in the braking process of the large inertia slewing mechanism of construction machinery,considering the two working conditions of full-load braking and no-load braking,the introduction of high and low pressure accumulators combined with the high power density of the accumulator and the high energy density of the super capacitor characteristics,a composite electro-hydraulic energy recovery system is proposed,the principle of the system is analyzed,the parameters of the important components of the recovery unit are matched,and the AMESim software is used for simulation analysis.The results show that the rotation characteristics of the composite electro-hydraulic recovery system at each stage are basically the same as the original system.The flow rate and energy utilization rate can reach 75.59% and 67.43% in a standard cycle,which effectively reduces the pressure fluctuation of the rotary motor.The energy-saving effect is good,which provides a reference for further research on energy-saving technology of construction machinery.