In order to minimize the fuel consumption, the topology optimization and sizing optimization are applied in the light-weight design of frame for energy-saving vehicle. The investigation consists of two stages. In the first stage, the static analysis and topology optimization were carried on the original frame to obtain the optimal layout. Then the sizing optimization was explored to find the feasible section dimension of beam. The simulation results revealed that the stress concentration and excessive local deformation of vehicle frame structure have been remarkably improved, meanwhile, the frame’s weight has been decreased more than 15.0%. It is concluded that the optimization method is effective to obtain the optimal light-weight design for vehicle frame.