The forktype hydraulic steering gear system is taken as a research object. The hydraulic system model of steering gear was established with AMESim software and the torque model of steering gear was established with Simulink software, and the steering torque and hydraulic cylinder pressure difference were analyzed in the cosimulation. The results show that the steering torque and the hydraulic cylinder pressure increase with the rudder angle, the steering torque is more influenced by the ship speed and draft when rudder angle is in the large area, and the hydraulic cylinder pressure is less affected by the ship speed and draft when rudder angle is in the small area.