The invention relates to a pressure-resistant structure of a large-depth submersible. The pressure-resistant structure is of a combined structure form, and comprises an inner shell, an outer shell, aleft flange and a right flange, wherein the inner shell is of a main force bearing structure, the inner shell is formed by winding on the basis of the left flange and the right flange, the outer shellis formed by rolling a titanium alloy plate and welding the titanium alloy plate through a longitudinal weld joint and is tightly attached to an inner shell ring rib, and the outer shell is connectedwith the left flange and the right flange through circumferential weld joints at the two ends. The inner shell is of a cylinder and outer ring rib structure, outer ring ribs are distributed at equalintervals, and the specific intervals are optimally configured according to the minimum stress criterion of a pressure-resistant structure when external pressure is borne. The inner shell and the outer shell are connected through the butt joint circumferential weld joint, the weld joint only bears tension and pressure, and the stress form is simple. The submersible has a large-depth pressure-resistant structure which is high in underwater pressure resistance, good in pressure-resistant stability, uniform in pressure-resistant stress, light in weight, high in specific strength, good in impact resistance, long in seawater corrosion resistance duration, long in service life, non-magnetic and good in concealment.