The hydraulic system of excavator has problems such as pipeline loss,overflow loss,throttling loss and leakage loss,which lead to large power loss and low energy utilization rate in the process of excavator operation.To improve the power utilization of excavator hydraulic system,taking the positive flow excavator as the research object,the electromechanical hydraulic joint simulation platform was established.Aiming at the problem of large pressure loss of multi-way valve,the method of changing the flow area of the main valve special-shaped valve port area was proposed,which reduced the local pressure loss and improved the power utilization rate of the hydraulic system.Taking the bucket linkage as an example,changing the flow area of the inlet and outlet of the bucket main valve and the bucket confluence valve and the matching between them,the driving efficiency of the bucket action is increased by 4%,and the power loss of the hydraulic system is reduced.