Aileron is a device to simulate the support stiffness of aileron actuator. It is a key device in aviation ground load test. The research on the variation law of aileron stiffness simulator with position is beneficial to its design and application, and has important engineering value. In this paper, the mathematical model is established, the stiffness reduction factor is proposed, and the stiffness characteristics of the stiffness simulator are discussed; the stiffness simulation of the simulator is carried out, and the correctness of the mathematical model and simulation is verified through the stiffness test; the thickness of the simulator is optimized based on the sensitivity of the target stiffness to the distance. The results show that the stiffness reduction factor can quickly predict the stiffness characteristics of the simulator, and 7mm is the optimal thickness of this model stiffness plate.