In order to solve the problem that the outlet of traditional accumulator can not provide stable pressure oil in the process of discharging energy, which leads to the low energy reuse efficiency of the accumulator,a double bladder accumulator with constant outlet pressure was presented,which was used in the boom energy regeneration system of asymmetric pump controlled hydraulic excavator.The simulation model was established in AMESim software for verification, and then it was compared with ordinary accumulator. The results show that under the condition of reasonable matching of parameters, the new accumulator can provide stable pressure oil for the system;compared with the ordinary accumulator, the new accumulator can release 25% more energy, the motor power can be reduced by 9.85%, and the motor energy can be saved by 6.9%.