Abstract: Abstract： In this paper, a riskbased structural design method was discussed according to the risk beyond the submerged depth of submarines in the process of diving. First, the development of the structural design theory was expounded and the idea of riskbased structural design was presented. Then, the risk beyond the submerged depth was defined and the riskbased structural design criteria was developed according to the risk attitude of individuals, society, economy and the environment. Finally, the risk probability on different diving depths were calculated using the extreme value I distribution. The reliability optimization design model of the pressure hull was established and the design load curves with the increase of pressure hull structural weight was drawn. The design scheme for pressure hull was made based on the “costbenefit” principle.

Key words: beyond the submerged depth, structural design method, pressure hull, reliability, costbenefit