Based on in-depth analysis of structure and principle about mandrel supporting device of rolling tube machine, AMESim was used to make position closed-loop control hydraulic system dynamics modeling and simulation.The comparison of simulation results and the measured data validates the simulation method is correct and guiding to design. Through the use of AMESim two-dimensional simulation environment, exercise and process of real device can be displayed before system design. It provides reference for the design of hydraulic machinery and equipment.