There are many types of car suspensions control, H infinity control of vehicle suspension is studied in the literature for a brave time ago. We can define active suspensions as control systems incorporating a parallel spring and an electronically controlled damper. The contribution of this paper relies on H infinity control design to improve comfort and road holding of the car, and on control validation through Simulation on an quarter Car and Half Car model with seat-passengers of the suspensions system. In this paper an H infinity controller is designed for a actuated active Suspension system of a quarter-modelled and half-modelled with seat-passengers vehicle in a cascade feedback Structure, two H infinity controllers are designed for this system for two different model of suspensions. in this paper we will make a comparison between application of quarter car and half car model.