NOVELTY - Coke-oven gas is purified, compressed, heat-exchanged, and supplied to a methanol synthesizing tower. The gas from methanol synthesis tower is heat-exchanged and cooled to obtain crude methanol. Crude methanol is supplied to a rectifying tower to obtain fine methanol gas. Methanation reaction is carried out in the catalyst layer methanation reaction furnace to make carbon monoxide and carbon dioxide and hydrogen in the gas generate methane. Carbon oxide is removed and the mixed gas is gas-separated to obtain hydrogen.    USE - Cogeneration of liquefied synthetic natural gas.    ADVANTAGE - The method reduces the content of carbon oxide gas, enables recovery of resource to obtain methanol product, provides high recovery of hydrogen resource, and provides liquefied natural gas which can be conveniently transported.    DETAILED DESCRIPTION - Coke-oven gas is purified, compressed to 10-12 MPa, heat-exchanged via a heat exchanger, and supplied to a methanol synthesizing tower. The gas from methanol synthesis tower is heat-exchanged by the heat exchanger and cooled to obtain crude methanol. Crude methanol is supplied to a rectifying tower for refining to obtain fine methanol gas entering the alcohol washing device. Micro-methanol in the gas is washed off with water, and hydrogen and remaining gas are supplied to the methanation heat exchanger. The recycled heat is supplied to a preheater. A small amount of water condensed in the preheater is added in methanation reaction and methanation reaction is carried out in the catalyst layer methanation reaction furnace to make carbon monoxide and carbon dioxide and hydrogen in the gas generate methane. Carbon oxide is removed to obtain a portion of nitrogen and a mixed gas of methane. The mixed gas is supplied to a pressure swing adsorption device and membrane separation device for gas separation, to obtain hydrogen and mixed gas of methane-nitrogen. Hydrogen is separated and methane-nitrogen mixed gas is low-temperature liquefied to obtain liquefied natural gas.