Taking the open mill roller hydraulic driven system as the study object, the advantages of the hydraulic driven open mill were described, how it worked and related job requirements were analyzed. Through calculation, the relevant parameters of the pump and motor were determined, and AMESim software was used to make simulation research of the hydraulic system.The pressure curves at both ends of the hydraulic motor, motor flow curve and roller speed curve were plotted, the final simulation results were analyzed in detail. The results show that the hydraulic system design is reasonable, the output parameters meet expectations.