In hydraulic excavator operation process, the swing system frequently starts and brakes. Because of the large inertia and high starting pressure of the system, a large amount of overflow loss is caused; when braking, the kinetic energy of the swing system is transformed into heat energy through the brake valve of the hydraulic motor outlet, which wastes a lot of energy. In order to reduce the energy consumption in the process of excavator swing, the hydraulicelectric hybrid excavator swing drive system was proposed. In the process of swing, the motor was used as the main drive to control the swing speed of the swing system, the hydraulic motoraccumulator was used to recover the braking kinetic energy of the swing system and assist the motor to drive the swing system when starting. The parameters of the main components were designed, then a co-simulation model of the original swing system and the proposed system was established. The operating characteristics and energy consumption characteristics of the two swing systems were studied. The results show that the energy consumption of the proposed system is reduced by 37.26%~53.29% within a swing working cycle compared with the original system, and the backswing phenomenon of the swing system is suppressed, thus the operation stability of the whole machine was improved.