In order to achieve steering portability, security and comfort, the hydraulic steering system must have good stability, flexible steering and fast response speed of dynamic response characteristics, such as requiring proportional valve can be stable, fast reversing and control flow. Based on this, AMESim and Simulink were used in unity for simulation analysis of the response characteristic of the oil cylinder under different parameters, and the damping hole diameter of electro hydraulic proportional directional valve influenced of the response characteristics of hydraulic steering was researched. The results show that the damping hole within 2~10 mm in diameter, with the increase of damping hole diameter, the longer time is for reaching the designated position, that is the slower of the response speed. When damping hole in 1 mm of diameter, its overshoot is rather high. When damping hole within 8~10 mm in diameter, the hydraulic cylinder has a small amount of vibration.