Based on the dynamic model of 1/4 vehicle suspension, a control model is designed by using the fractional order exponential reaching law of the model following variable structure control strategy. The parameters of the sliding mode switching surface are designed by the pole assignment method. The fractional order exponential reaching law is set by using the definition and properties of basic fractional exponential differential equations and F-functions, and then the control force of the active control law and semi-active control law are obtained according to whether the output force of the controller is restrained or not. Modeling and simulations are performed in Matlab, and the results show that compared to the passive suspension, the main performance indicators are reduced, meanwhile it is able to track the reference model; and compared with the integer exponential reaching law, it has better relative stability, robustness and more effective attenuation chattering. The simulation also verifies that the semi-active control can achieve the results of active control, but there are certain local fluctuations.