In order to realize the lightweight design of heavy dump trucks,through the finite element modeling of the dump truck as a whole. Carry out four kinds of transportation and unloading conditions under the load of stiffness and strength analysis and vehicle modal performance analysis, evaluate the performance requirements of the vehicle under static and dynamic conditions. Calculate the sensitivity of displacement, strength, mode and mass of the whole vehicle components, and define the relative sensitivity. Using the results of the relative sensitivity analysis to determine the optimal design variables, while ensuring the vehicle just under the premise of strength and low order modal frequency, size optimization and shape optimization of vehicle structure combining optimization method.The results show that the static and dynamic characteristics of the vehicle are significantly improved after optimization, and the total mass is reduced by 10.2%. The feasibility of the lightweight design method is verified.