The efficiency influencing factors of the valve control section of valve and pump combined electrical hydraulic actuator (EHA) were analyzed. The method to improve the system efficiency by decreasing the design value of source pressure was proposed. According to the working characteristics of the pump and valve combined EHA, the change of output flow, losing flow of servo valve and pump, total efficiency of actuation system and other main performance parameters caused by source pressure change were analyzed at the same working condition. The result indicates that the system efficiency is improved and the power loss caused by losing flow is reduced in some range. The rapidity and stability become better, the disturbance rejection becomes worse, so that the efficiency and performance should be considered integrated. The simulation testing of actuation system based on spring load proves the feasibility of new method.