The suspension system of any vehicle has the task of not only supporting the weight of the vehicle, but also improving the ride comfort and stability of the vehicle by reducing the roughness of the road before transferring it to the passengers.When the car encounters a rough road, the suspension system should not make too many oscillations, and even if it does, these oscillations should be eliminated as quickly as possible.n this paper, the suspension system, its functions, components and types, including passive, semi-active and active, have been investigated, and more specifically, the performance of the semi-active suspension system of a passenger car by modeling it as a semi-active suspension system of a quarter car been investigated.This model is designed as a semi-active suspension system based on PID controller and MATLAB Simulink is used in this process.The system considered in this paper linear system that can check the basic functional parameters of a suspension system such as body movement and suspension and passenger acceleration and provide the results in terms of rise time, settling time and overshoot. Ride comfort and car stability are known as the two goals of the suspension system, which can be determined by the amount of overshoot and settling time of the body displacement, the body acceleration, the displacement of the suspension system relative to the road, and the displacement of the body relative to the suspension system.Also, these performance indicators are compared with a passive suspension system with similar specifications.The results obtained through simulation show that the semi-active suspension system using a PID controller designed to adjust its damping parameters has a much better performance than the passive system with constant damping.