NOVELTY - Hydrogen and methane (CH4) are extracted from coke oven gas by compressing coke oven gas to 0.12-0.15 MPa and cooling to 20-40 degrees C for removing sulfur, benzene, naphthalene and tar; hydrolyzing coke oven gas to remove hydrogen sulfide (H2S); removing carbon dioxide (CO2); removing sulfide, mercury, moisture and high-carbon compounds by absorption method; entering coke oven gas to a membrane separator to separate hydrogen, compressing separated hydrogen and performing hydrogen liquefaction; and entering coke oven gas into a low-temperature rectification column to extract liquid methane.    USE - Method for extracting hydrogen and methane from coke oven gas (claimed).    DETAILED DESCRIPTION - Extraction of hydrogen and CH4 from coke oven gas comprises:    (A) compressing coke oven gas to 0.12-0.15 MPa and cooling to 20-40 degrees C for removing sulfur, benzene, naphthalene and tar through crude desulfurization and pretreatment;    (B) compressing coke oven gas to 2.2-4 MPa for hydrolysis to remove H2S;    (C) applying N-methyl diethanolamine to remove CO2 from hydrolyzed coke oven gas by a wet method to reduce the content of the CO2 in the coke oven gas to trace amount;    (D) applying an absorption method to remove sulfide, mercury, moisture and high-carbon compounds (more than 5C) from the CO2-removed coke oven gas;    (E) entering coke oven gas to a membrane separator at 20-60 degrees C and pressure of 1.5-4 MPa for separating hydrogen from CH4, N2 and CO; and processing pressure swing absorption and purification to make the purity of the separated hydrogen reach 99.999%;    (F) compressing the separated hydrogen to 2-5 MPa and entering into a liquid hydrogen device for liquefaction comprising precooling liquid nitrogen to 60-90 K and then cooling to 20-30 K by a main heat exchanger of the liquid hydrogen device, reducing pressure to obtain the liquid hydrogen which is to be conveyed into a liquid hydrogen storage tank, heating and decompressing the liquid hydrogen to obtain hydrogen gas, where the separated hydrogen undergoes ortho-para hydrogen conversion at different temperatures using solid catalyst for accelerating speed and the solid catalyst is active carbon, metal oxide, iron hydroxide, nickel, chromium or manganese;    (G) allowing the coke oven gas that passed through membrane separator to enter a plate-type switching heat exchanger at 20-60 degrees C and 1.5-4 MPa, and lowering temperature to remove substance with boiling point above - 50 degrees C; and    (H) entering the coke oven gas into a low-temperature rectification column for heat exchange and mass exchange, where gas substance flows towards the column top while liquid substance flows towards the column bottom; extracting the liquid substance comprising liquid methane from mixture of methane (C1), ethane (C2) and propane (C3) from the column bottom and with purity of 98% and comprising less than 0.5% carbon monoxide; and heating the liquid methane to obtain methane gas.