According to the functional requirements of the amplitude changing mechanism control system of heavy duty manipulator,a hydraulic system was designed,which could be used to realize the synchronous displacement control of the amplitude changing mechanism.Combined with the displacement synchronization control method and strategy of heavy duty manipulator,a fuzzy neural PID control strategy was proposed,which could meet the requirements of system stability and robustness.AMESim and Simulink were used to model and simulate the variable amplitude control hydraulic system.The dynamic effects of fuzzy neural PID and conventional PID on the motion control of hydraulic cylinder were compared and analyzed,and the displacement curve of the hydraulic cylinder piston rod in the hydraulic system was obtained.The simulation results show that:the fuzzy neural PID controller has strong antiinterference ability and good robustness,which verifies that the synchronous displacement control hydraulic system with variable amplitude mechanism has good working performance