A controller design method based on nonlinear adaptive Backstepping is proposed for the vehicle semi-active suspension system containing parameter uncertainties and input saturation problem. This method realizes the compensation of the control saturation by introducing an auxiliary system and designing a new error variable, which solves the problem of amplitude constraint of the control input. Considering the parameter uncertainty of the suspension system, a control law is designed using a projection adaptive algorithm, and the stability of the suspension system is ensured by constructing the appropriate Lyapunov function. The simulation results show that the controller has good vibration isolation performance and can effectively reduce the influence of input constraint and uncertain parameters.