The force of control column is very important for the pilot in a flight simulator. So the control loading system in the flight simulator has been concerned since the flight simulator appeared. As the force command signal generated part of control loading system, flight control system module is the most important module for the fidelity of control loading system. This paper described a method to build flight control module. We used SimMechanics in simulink to model and analyze the feel and centering unit, which is the key part of feeling system in the flight control system, and in this paper we described the structure of the control loading system, and the function of the feel and centering unit.