Completely different from the design of conventional ships, the dismountable assembling ship adopts the modular assembly and disassembly, and the bolt connection is adopted for each module, which cannot be solved by the existing rules. The principles of the equivalent strength of hull girder and bolt and the equivalent strength of transverse structure and bolt are proposed based on the basic mechanical principle and the corresponding equivalent principle. The bolt strength of the overall longitudinal and the transverse strength of the hull is solved scientifically and reasonably by combing the two equivalent strength principles and the finite element method. The drawing review of the hull structure design can be successfully solved by the method that is proposed in this paper, which can provide reference for the design of this kind of dismountable assembling ships.