To improve the efficiency of driving system applied in hybrid or electric hydraulic excavators, a parameter matching method was developed to optimize the system which is adopting the pump controlled technology with energy recovery technology．Structure and working condition were analyzed as well. Then, considering the saving the space of energy accumulator when installed, flux matching of the cylinder when boom goes up asymmetrically and extending the working life of the energy accumulator, parameter matching of the low energy density of the accumulator, motor, generator etc. for the energy-saving system proposed was discussed. The matching results were analyzed using the model built in AMEsim software. The results show that the close loop energy-saving can be around 55% because there is no throttling loss and the potential energy of the boom can be regenerated. Not only can the excavator boom be controlled without valve but also the energy recycles under the negative pressure condition for excavator.