Over the past few years, active suspension system on motor vehicles has had an in increasing application. The simulation of this system has a multiple importance, especially in the countries such as ours: We gain time - by not having to wait for exploitation results; It is cost-effective - we don't have to design an expensive model in the Lab and perform complex laboratory examinations; We can simulate suspension systems of almost all categories and kinds of motor vehicles, which could, also, be hardly possible in laboratory conditions. Suspension system modelling has been performed on ¼ vehicle model, using Matlab program, version 5.2, in two different ways: by transfer function and state-space equation. It has been concluded that the settling time and overshoot of the vehicle, after coming across any kind of obstacle, are too long, and that a controller must be introduced into the suspension system. We have designed a system with PID controller and found the response of such a system. Then we have chosen the poles and zeros for such a controller and designed it using root locus design method. Finally have performed the synthesis of the system in the frequency range as well, using Bode plot or via Nyquist diagram. All of these simulations have been carried out for passenger vehicles and for buses. WE have optimized the controller characteristics relative to initial concrete requirements and on the basis of different values of input parametres. We expect that, in near future, this design and some of its modifications, will have a large application in the designing of such suspension systems in motor vehicles industry of our country.