Abstract: In order to gain more precise optimization design of the 400 t heavy-duty mining dump truck's steering system, meanwhile considering dynamic stiffness characteristic of suspension cylinder and nonlinear characteristic of tire, this paper coupled steering mechanism, suspension and tire these three motion fields, then established the mathematical model of steering system for multi-objective optimization. With the use of physical programming method, the physical programming optimal design model of steering system was established, and the optimal solution and preliminary screening were achieved with genetic algorithm. At last, the Trucksim were used to handle stability simulations, which is the emergency double-lane change test. It ultimately selected the optimal solution for design of steering system, and provided a new method for determining the optimal solution.