Abstract: In order to effectively recycle the BOG produced by LNG terminal and reduce its emission, a simulation is made for the BOG compression and reliquefaction process in a LNG terminal in China. With the operating parameters under the HYSYS-simulated conditions, this paper analyzes the influences of some parameters on the reliquefaction system, including the methane content and component proportion of mixed refrigerant, outlet pressure of BOG compressor, and outlet pressure of refrigerant compressor. Accordingly, the recommended proportion of mixed refrigerant is: 24% methane, 12% nitrogen, 33% ethylene and 31% iso-butane; the outlet pressure of two-stage refrigerant compressor is 4 300 kPa, the outlet pressure of two-stage BOG compressor is 7 200 kPa and throttling pressure is 370 kPa. Under the above conditions, the system's power consumption is 664.935 kW, which is reduced by 8.45% from previous level.