A mathematical model of 1/2 vehicle semi-active suspension has been built by abstraction and simplification, followed by the establishment of a simulation model in MATLAB software. The final results of the sprung mass, speed and change rate of passive suspension, which are to be taken as the output of active suspension control, has been worked out. The fuzzy PID compound controller has been adopted by the semi-active suspension, for the purpose of the adjustment of the PID controller online in the given parameter range. The results show that the semi-active suspension with the fuzzy PID controller has an evident effect on the improvement of the overall vehicle performance at different speed stages, with the body vertical acceleration, body pitch angle acceleration, as well as the front and rear suspension moving stroke obviously improved, thus helping to improve the ride comfort and handling stability of the vehicle in different speed ranges.