Abstract: Objectives Non-pressure shipboard tank is an important component of dual-hull submarine. With the increasing diving depth, in order to reduce the structure weight and increase the effective loading, the structural form of non-pressure shipboard tank of submarine need to be optimized. Methods In this paper, the thickness, frame spacing, the section dimensions of stiffener of non-pressure shipboard tank are selected as design variables, the structural strength, stability and geometrical requirements are set as constraints while the total volume of the structure is determined as objective function. Based on the simulated-annealing algorithm, A special code and Optimization Tool are both used to make an optimization plan for transverse non-pressure shipboard tank using MATLAB program. Results Under the requirement of recent code and standard, the result indicates that the structure volume of optimized plan is 27.2 percent reduction compared to the original plan, and qualitative analysis is conducted for the optimized design results. Conclusions The research results can provide references for the design of non-pressure shipboard tank.