For large excavator hydraulic oil return back pressure system containing Bosch rexroth back pressure valve assembly,hydraulic oil temperature is high and the hydraulic oil radiator occurs oil leakage failure phenomenon after it was used 800~1 200 h.To solve the problem,through adding components on the outside pipe,such as check valve,throttle valve,the maximum working pressure setting in oil return back pressure valve control cavity and fast charging and discharging of hydraulic oil were achieved.The opening pressure overshoot of the check valve was reduce to avoid the occurrence of faults.The experimental results show that the scheme is simple and feasible with low cost,and the utility model patent (CN216199383U) has been granted.It has been popularized and applied in medium and large hydraulic excavators of a company.