Abstract: An active hydropneumatic anti-roll system is developed to reduce the roll angle of a passenger car with air suspension system. Due to its simple structure and low cost, an electromagnetic on-off valve is selected as an actuator element. Correspondingly, four discrete control methods are compared with the simulation model that a quick, exact and efficient movement of anti-roll system is realized with a simple control loop. Simulation results showed that the control loop is simple with the three point control method. But the precision of piston movement is low and the valve is switched frequently. With the PWM and PID control method, the movement of piston is controlled exactly and the time of switching is reduced. For the least switching time, the sliding mode control method is recommended preferentially, but the precision of piston movement is reduced too.