In order to solve the problem of the low energy utilization efficiency of valvecontrolled hydraulic system of hydraulic excavator, a hydraulic energy saving system based on hydraulic transformer was proposed and its energy saving effect was researched. The energy consumption of the valvecontrolled hydraulic system and the hydraulic energysaving system based on the hydraulic transformer were researched by using AMESim and AMESim-MATLAB respectively; the energy utilization efficiency and energy saving effect of the valvecontrolled hydraulic system and the hydraulic energy saving system were compared and analyzed. The results show that the hydraulic energy saving system using hydraulic transformer as the main control element has relatively good dynamic performance, and the energy utilization rate is significantly improved compared with the valvecontrolled hydraulic system, and the energy saving effect is excellent, which can provide reference for the energy saving optimization of hydraulic excavator and the reduction of the installed power of the system.