To realize the space planes, there is a need for a system analysis considering the trajectory and airframe design at the same time. In this study, for applications to airframe design applying a waverider which has high performance at hypersonic region, it was carried out design and trajectory optimization at the same time. As a specific mission, we designed the booster to accelerate the orbiter of 45ton to transport a payload of 0.8ton to LEO to Mach 12. As the result, we obtained booster the weight of 442ton. The result showed that it was important to consider about the small thrust in trajectory and trim balance when airframe design was performed.