Abstract: The calculation model of BOG production in the loading process of small LNG carrier has been established by using the steady-state module of the process simulation software, and the influence trend of the factors such as the operating pressure of storage tank at LNG receiving station and the operating pressure of storage tank on the BOG production of the loading process has been studied. The dynamic model of loading process has been established by using the dynamic module of process simulation software. The parameters of storage tank temperature, pressure and BOG return during the loading process is simulated. The simulation results show that the operation pressure difference between LNG carrier storage tank and LNG tank is the key parameter to influence BOG produced or not, and the LNG carrier storage tank reasonable operation pressure could achieve win-win results for both suppliers and purchasers of LNG.