A system and a method for circulating the LNG of a LNG carrier is provided to make a stable and safe operation of a flow rate control valve and a temperature control valve. A system for circulating the LNG of a LNG carrier comprises a LNG cycle line(L5). The LNG cycle line is installed at a liquid transfer line(L2). The liquid transfer line is connected between a LNG storage tank and the outside to transfer the liquid LNG. The LNG cycle line draws out LNG from the LNG storage tank. The drawn out LNG is again restored to the LNG storage tank after the liquid transfer line pass.
