The function of a front underbody is to minize a damage of vehicle by absorbing the kinetic energy for frontal impact. By using aluminum as lightweight material and the roll forming process, the weight reduction as well as requirements of regulations defining the performance level can be achieved. This paper show the development of light-weight front under body for frontal impact with design optimization such as topology optimization and size optimization, and high strength steel(980MPA) on front side member by roll forming process. In conclusion, we could achieve weight reduction of about 8.8kg with a high efficiency crashworthness.