Abstract: In order to study dynamic response characteristics of hydraulic rotary system for azimuth vector thrusters,the composition and working principle of an azimuth thruster were analyzed,studying the pumping-controlled hydraulic motor drive gear reduction mechanism. A mathematical model was established for the rotary dynamics system of vector thrusters. An improved control method was proposed for the vector thrusters to achieve a desired azimuth angle tracking. An asynchronous control frequency simulation system was established for the vector thrusters to analyze the azimuth angle,angular velocity and the dynamic response characteristics of hydraulic rotary system under different azimuth angle. Based on the simulation analysis,the physical constraints of the rotary response were established for the vector thrusters. Simulation results show that,the proposed dynamic model can realistically simulate the dynamic characteristics of azimuth dynamics,and can achieve fast and accurate control of the azimuth angle. Compared with the actual propeller response parameters,the efficiency of the rotary control of an azimuth thruster is improved,and the research on thrust allocation method of dynamic positioning ships and the control of azimuth thrusters has important theoretical significance and engineering value.