Subjected to high axial compressive load and internal pressure，the stiffened waffle cylindrical tankage forms part of the primary structure of missiles and launch vehicles. In this paper every possible failure caused by such structure and an optimum design method is presented. Results of numerical examples by this method indicate that the weight of the structure to decrease by 17.3% as compared with that of the stiffened waffle cylindrical shell made by chemical milling under the same load.