By using controllable suspension,the consideration for off-road vehicle is given to both on road and cross-country.Controllable suspension can be divided into body height control suspension,active suspension,semi-active suspension and slow-active suspension.For off-road vehicles,the slow-active suspension is the most appropriate.The development of control theories for controllable suspension has gone alone with the development of modern control theory,and the development trend of suspension control is that two or more original control methods are integrated to become a new control method.Now,the RD of controllable suspension for military or civilian off-road vehicle are just in experiment.