Abstract: A dynamic model of LNG truck loading process had been developed using the process simulation software HYSYS Dynamic, where the parameters such as pressure, temperature and flow rate of BOG produced by two different loading modes were researched and simulated. The simulation results showed that: the truck loading without gas-returned mode had the characteristics of higher tank pressure, less loading volume, less BOG generation, low operation cost and less unloading time after finishing truck loading, which was highly economical and feasible.