In order to solve the problem of complex nonlinear vibration response in the traveling vehicle system， a nonlinear dynam? ical model for a coupled human-vehicle-road system with three-degree-of-freedom is established. The coupled vibration equations of human-vehicle-road with three-degree-of-freedom are derived by the Lagrange equation， and the sine and cosine functions of this system arise from the geometric nonlinearity of torsional deformation. The nonlinear restoring force surfaces， potential energy sur? faces and analytical expressions of natural frequency are obtained for the free vibration of the human-vehicle-road system. For the forced vibration， the influence of vehicle system parameters of vehicle mass， moment of inertia， passenger mass， seat stiffness， suspension stiffness， damping， centroid position， road wavelength and wave amplitude on the response curves of amplitude veloci? ty is analyzed by using the numerical simulation method. The experimental platform of the coupled human-vehicle-road vibration system is built and the reliability of theoretical analysis and numerical results is verified by the experiments. The results show that this nonlinear dynamical coupled system with three degree-of-freedom can accurately describe the human-vehicle-road response characteristics， and reasonable selection of the system parameters can effectively reduce the vibration response amplitude and im ? prove the human riding comfort.