Abstract:The combined sphere-cylinder hull is the main form of pressure hull structure for single-hull submarines, and its structure’s ultimate load carrying capacity and deformation under extreme loads are important indexes to evaluate the safety of sub- marine structures. Based on the test model, according to the actual measurement data of the 3D initial deflection, the finite element models of combined sphere-cylinder hull are constructed. The calculated results of ultimate strength are validated against the experi- mental results. The result shows that the said method is credible and reliable for numerical prediction, and it has practical signifi- cance to introduce deflections into the evaluation of ultimate load carrying capacity of submarine structures.