Abstract: Method for liquefying a gas (12) to be processed comprising at least 50% by volume of methane, comprising the following steps: purification of the gas to be processed, precooling of the purified gas (22) to a temperature less than or equal to ?15° C. by heat exchange with a precooling refrigeration cycle (40), liquefaction of the precooled gas (26), in a liquefaction unit (30), into a liquid stream (32), with subcooling less than or equal to 5° C., the liquefaction unit including a Stirling refrigeration cycle (50) distinct from the precooling refrigeration cycle, this cycle using a first refrigerant (42) precooled by a precooling refrigeration cycle (40) distinct from a Stirling cycle, subcooling of the liquid stream, and expansion of the subcooled liquid stream (36) to obtain a liquefied gas (14).