Based on one LNG terminal boil off gas (BOG) recovery with high energy consumption, the relationship between the pressure of LNG tank and the control load of BOG compressor is analyzed. The optimization of operation mode of BOG system isproposed. After optimized operation, the tank pressure remains stable, and the stability of BOG evaporation is increased, which prevents BOG compressor from running at the fully capacity. At the same time, LNG terminal energy consumption is reduced, economic benefits is also increased. This method can provide reference for the operation of other LNG terminals.