Hydraulic winch volume speedmodulating system was established. The components of this system included the limit variablepressure oil pump, accumulator tank and variable hydraulic motor controlled by electrohydraulic proportional servo valve. Using AMESim software, a hydraulic winch proportional servo control system simulation model was built, and the simulation research on the system performance was done. The results show that the speedmodulating system has good speed tracking feature, high speed control accuracy and systems stability, also has a significant energy saving.