The vehicle suspension system considering time delay is taken as the research object, and the combination methods of theory and experiment is used to study the vibration characteristics of vehicle suspension system. Firstly, a matrix inequality for system asymptotic stability is derived by using the Lyapunov-Krasovskii functional and free-weighting matrix method. Based on the matrix inequality, a H∞ controller is designed for the system with known maximum time delay. Then, the proposed control strategy is used to solve the control problem of the active suspension system. Numerical simulation and experimental methods are used to verify the time-delay control strategy. The results show that the control law in this paper can effectively suppress the sprung mass acceleration. Finally, the relationship between the time delay and the RMS value of the sprung mass acceleration under different gains is analyzed. It's found that a better control effect could be obtained when the difference between d and τ is small.