This article deals with the problem of controlling the stiffness of the air suspension system to help stabilize the body when the vehicle is moving around. Through the simulation of the change of the suspension stiffness parameter using Matlab simulink software, this paper has shown the impact of external force on the change of air suspension stiffness through simulation graphs. Based on the specifications of the Thaco Mobihome vehicle, simulation results have shown that there is a control to change the air suspension stiffness to help the vehicle move more stably and safely in the horizontal direction when the vehicle is moving around. From the results of this study, it has also been shown that the application of air suspension system for passenger cars will completely improve the level of stability and safety for passengers.