Cycloid rotary valve control unit is the core of the whole hydraulic steering system, its static and dynamic characteristics have important influence on the performance of the steering system. According to the structure characteristic of the cycloid rotary valve control unit and the working principle of the whole hydraulic steering system, the model of the whole hydraulic steering system including the control unit was built based on AMESim. The static and dynamic characteristics of the control units and its influence on the system performance were analyzed, and the influence on the system performance under the steering wheel different input was also analyzed. The influences of viscous damping coefficient, effective volume elastic modulus and moment of inertia on the performance of the steering gear were analyzed. The test model of the whole hydraulic system was built, and the displacement of the steering system was analyzed. The analysis results show that: viscous damping coefficient and steering response is positively correlated, the peak of the latter response curve also shows a gradual increase when the former value is increased; when the effective fluid bulk modulus increases, fluctuation of the response curves is weakened gradually, and the steering performance is improved; when the moments of inertia increases gradually, the system adjust time is extended, fluctuation peak is increased, it is illustrated the response character becomes poor; the steering cylinder displacement has a certain delay relative to steering wheel angle and they are not exact linear relationship; the steering control unit’ parameters effects on steering system are consistent with test and simulation results, which verifies the accuracy of the simulation model.