Since buried locations of fuel oil and natural gas are moving much farther from land areas, methods for excavating and transporting energy are needed in the energy market. Thus, one of the alternative methods, Floating Production, Storage and Offloading (FPSO), is under development recently for transporting and supplying the energy from deep sea areas. Among those platforms, LNG-FPSO for the excavation of LNG will play a leading role in satisfying the demands of LNG in the near future. Because the LNG-FPSO is designed to handle all processing activities on a ship, many facilities and modules are installed next to other's equipment closely in a compact area. Thus, a single event on an offshore plant may lead to a complete disaster for the entire facility, called domino effects. This research suggests the selection method of the optimal layout for preventing domino effects by using a mixed integer linear programming (MILP) model as a mathematical approach. Also, weight balance for stability, which is an important issues in offshore platforms, is considered in the layout problem. The suggested method can secure the safety in the multi-floor offshore process and reduce the effort to find the optimal layout.