A new structural design technology has been recently developed to build a new type of land vehicle in military use. While thick panels are only employed in conventional land vehicle structures, solid frames combined with relatively thin composite panels are employed for the new type of vehicle. The structural integrity of the new vehicle structure type is mainly guaranteed by the solid frames while composite panels are used to protect passengers and equipments of the vehicle. To design such a frame-panel structure, frame design needs to be done first. In this paper, a two-stage design process is proposed employing topology and cross section optimization methods. Overall frame arrangement of the new vehicle structure is obtained by the topology optimization in the first design stage and the detailed dimensions of the frames are obtained by the cross section optimization in the second design stage.