With the development of driverless cars, the demand for the high response speed, precision and stability of the car’〖KG-*2〗s steering system is getting higher and higher. The slide valve pressureflow characteristics of asymmetric cylinder controlled by proportional valve, flow continuity equation of cylinder controlled by proportional valve and force balance equation of hydraulic cylinder were analyzed. The steering resistance moment of the steering system was analyzed. The mathematical model of the hydraulic steering system of dual valve control asymmetric cylinder was established. Time domain and frequency domain characteristics of the system were analyzed by using MATLAB/Simulink. A data acquisition program for the experiment platform system was developed. The data of the steering experiment system platform was collected and the results were analyzed.The comparison of simulation results and experiment results shows that the system meets the engineering requirements.The simulation results are consistent with the experimental results and the model is accurate.