Abstract:A half-car model of semi-active suspension systems with 4-DOF was designed in Matlab, and a fuzzy hybrid controller was built. Then, the membership functions and rule of fuzzy hybrid control strategy were optimized by particle swarm optimization (PSO).In order to verify the proposed control strategy, a series of experiments of PSO-fuzzy-hybrid control strategy on the platform of hardware-in-the-loop were carried out.It showed that compared with traditional fuzzy control strategy, PSO-fuzzy-hybrid control strategy enhanced the overall performance of the semi-active suspension system effectively, and obtained better control performance in all different road input excitations.