Maintainability of a mechanical system is one of the system design parameters that has a great impact in terms of ease of maintenance. In this paper, a methodology of facility layout optimum design for maintainability of a ship cabin is presented as a way to improve the efficiency and quality of maintainability design. The maintenance operating space, amount of hoisting, balance of cabin, ... [Show full abstract] distance requirement and personnel movement distance are all taken into account, and treated as objective functions. The mechanical functional constraints and some important layout experience are also considered and formulated as constraints. Thus, the mathematical model for maintainability layout combinatorial optimisation is constructed. According to the characteristics of maintainability-based facility layout problem, the particle swarm optimisation algorithm developed by Eberhart and Kennedy is modified to enhance the computational efficiency and solution accuracy. A hybrid position updating method is used to solve the optimisation problem with both continuous and discrete variables. The dynamic neighbourhood structure, dynamic inertia weight and adaptive mutation mode are modified to effectively solve the optimisation problem with multiple peak values. Finally, the methodology proposed is illustrated by simulation case and engineering application, and the results suggest that the methodology is effective.