Proper handling of boil-off gas (BOG) during normal operations as well as ship unloading significantly affects the efficiency of the operation and the safety of the whole gasification plant. Optimal operations of BOG compressors need to consider multiple aspects of plant safety and reduced power consumption, simultaneously satisfying all process requirements and constraints. However, due to the not-well-known characteristics of the involved dynamics, it is suspected that the BOG compressors are being operated in too great a capacity, unnecessarily consuming too much energy. A method for optimization of BOG compressor operation is proposed in this paper, which minimizes power consumption based on a mixed integer linear problem (MILP) formulation and refines the operation policies based on a safety analysis on the dynamics of the tank pressure. The proposed method is expected to be able to contribute to improving the efficiency of the whole liquefied natural gas (LNG) gasification plant operation and control.