Proposed in this paper is an automatic-centering rotary platform for a kind of planar movable stereo car garage,and its automatic centering principle and hydraulic system circuit are analyzed.Then,a power mechanism model of the asymmetric hydraulic cylinder controlled by the symmetric valve is constructed,and a transfer function between the piston rod displacement of the hydraulic cylinder and the spool displacement of the servo-valve is de- rived.Moreover,a model of the hydraulic system and a model of the input signal are constructed respectively by u- sing AMESim and Simulink,and an open-loop transfer function between the input signal and the piston rod dis- placement is deduced to verify the stability of the closed-loop system.Finally,the dynamic characteristics of the hydraulic system circuit is collaboratively simulated by using AMESim/Simulink,thus achieving the displacement curves and displacement error curves of two piston rods under different input conditions.Simulation results demon- strate that，for the displacement of the two piston rods,there exists a certain distortion,but it is a normal phenome- non,which means that the proposed platform is both feasible and effective.