General instability is one of the important collapse modes of cylindrical shells reinforced by ring stiffners under uniform pressure. Few research, however, has appeared in this field because of difficulties and complexity of the problem. Pressure hulls of deep diving submersibles have been designed on the basis of research works which were developed under idealized conditions for boundaries, stress-strain relations, and geometries. Recently, the development of high strength materials and the increase of operating pressure and diameter of pressure hulls have brought a change in proportion of primary structural members of cylindrical ring-reinforced shells, which leads to the review of the design procedure. In order to satisfy the above-mentioned requirements, pressure hulls should be designed on a reasonable basis. In the present paper, the elasto-plastic analysis of the general instability of ring reinforced cylindrical shells is performed on the basis of the finite element method, and results obtained are compared with collapse tests using two machined models and one welded model, which shows good coincidence with the theory. On the basis of a series of calculation, the authors propose a design criteria for the pressure hulls of deep diving submersibles. Futheremore, they investigate the influence of boundary conditions and initial imperfections on the general instability theoretically.