Abstract: In order to meet with wide variations in roads conditions controllable stiffness elastic elements are reguired in the suspension of vehicles.Stiff mathematical models of hydropneumatic springs show that some relevant factors such as the volume of gas accumulator and the temperature of operational environment markedly affect the stiffness of hydropneumatic springs.The total volume of gas accumulator can be controlled by changing the number of gas accumulators,and the stiffness of hydropneumatic spring can be controlled furthermore.Stiffness analysis of controllable stiffness hydropneumatic spring shows that controllable stiffness hydropneumatic spring can be used to improve riding comfort and environmental temperature adaptability of vehicles.