In order to improve the heavy-duty transportation vehicle drivers′ riding comfort and driving safety, a fuzzy sliding mode controller for semi-active suspension based on a new reaching law was put forward. Firstly, to solve the problem of real-time measurement of road signals, based on the improved reference ceiling model, the motion state of the unsprung mass was directly used as the input of the control system; secondly, aiming at the problems of chattering and slow convergence speed of the system caused by sliding mode control, a new reaching law of the saturation function of the variable boundary layer was proposed, and the fuzzy control and sliding mode control were combined to ensure the control accuracy and control robustness; finally, the semi-active suspension of the heavy-duty transport vehicle was simulated. The results show that compared with traditional fuzzy sliding mode control, the vertical acceleration of the body is reduced by 789%, the dynamic load of the wheel is reduced by 136%, and the dynamic deflection of the suspension is reduced by 314%. The proposed controller can improve the riding comfort which is evaluated by the vertical acceleration of the body and the dynamic deflection of the suspension, and the driving safety which is evaluated by the dynamic load of the wheel, providing some reference for the study of the intelligent control of semi-active suspension system.