The steering system, suspension system, and braking system of the vehicle are interrelated, so the ride comfort and handling stability of the vehicle are also closely related. But the vertical and lateral dynamics equations and controls system of the vehicle are always independent of each other, and the multiobjective control is generally achieved through the coordination of control algorithms. In this paper, taking the dynamic load of the tire as a link, the vertical dynamic model and the lateral dynamic model of heavy-duty vehicle are coupled. When the heavy-duty vehicle is turning, the proposed coupling model not only reflects the influence of the front wheel angle on the vertical motion and the vertical tire load, but also reflects the unevenness of the road surface on vehicle lateral motion. In order to improve the handling stability and transient safety of the vehicle, a synchronous control system combining six-wheel steering and front wheel active steering is proposed. It solves the problem that it is difficult to effectively track the desired yaw rate for the three-axle all-wheel steering vehicle with the middle rear wheel angle as the control input. Under the framework of the vehicle vertical/lateral unified coupling dynamics model, the semiactive suspension system controlled by fuzzy PID and the six-wheel active steering system combined with fuzzy control and fuzzy PID control are integrated. It is verified that the synchronous control method effectively optimizes the vertical and lateral motion characteristics of heavy-duty vehicles during steering and, at the same time, improves the ride comfort and steering stability.