According to the situation that 4 hydraulic cylinders of roller straightening machine are driven under synchronous pressure, based on the traditional closed loop synchronous control, a master-slave synchronous control scheme of one main and three subordinate hydraulic cylinders is proposed, and its basic principle is expounded.MATLAB/Simulink software was used to simulate the master-slave synchronous control of the roller straightening machine. The simulation results show that the average value of displacement fluctuation of hydraulic cylinder is 0.189 mm and the maximum value of fluctuation is 0.273 mm, while the average value of straightening pressure fluctuation is 0.6 MPa and the maximum value of fluctuation is 0.68 MPa.In the end, an experimental comparative study is made on the closed-loop synchronous control and master-slave synchronous control by relying on the 11roller straightening machine of Jigang. Through the analysis of the data of the levelling roller gap value and levelling force, it can be seen that, compared with the traditional closed-loop synchronous control, the master-slave synchronous control can achieve better position accuracy and straightening pressure control.