NOVELTY - Method for purifying ammonia synthesis gas and co-generating synthetic natural gas and/or liquefied natural gas involves cooling molecular sieve of crude hydrogen, introducing obtained material into flash tank, carrying out flash evaporation, introducing primary phase of flash tank from flash tank tower top into bottom of nitrogen washing tower, separating cooled high-pressure nitrogen in heat exchanger into two fraction, introducing one fraction high-pressure nitrogen into another heat exchanger, cooling, and removing carbon monoxide-rich liquid fraction.    USE - Method for purifying ammonia synthesis gas and co-generating synthetic natural gas and/or liquefied natural gas (claimed).    DETAILED DESCRIPTION - Method for purifying ammonia synthesis gas and co-generating synthetic natural gas and/or liquefied natural gas involves cooling molecular sieve of crude hydrogen through heat exchanger (H2) and heat exchanger (H3) at -180 degrees C to -190 degrees C, introducing obtained material into a raw material flash tank, carrying out flash evaporation to obtain gas phase (g1) and liquid phase (l1), introducing primary phase of raw material flash tank from top of the flash tank into bottom of the nitrogen washing tower, introducing high-pressure nitrogen through heat exchanger (H1), separating cooled high-pressure nitrogen in heat exchanger (H2) into two fraction, introducing one fraction high-pressure nitrogen into the heat exchanger (H3), and cooling at -180 degrees C to -190 degrees C, introducing obtained high-pressure and low-temperature liquid nitrogen into the nitrogen washing tower and contacting gas phase, removing primary phase carbon monoxide, arsenic and methane, removing secondary phase carbon monoxide, arsenic and methane, and carbon monoxide-rich liquid fraction, mixing secondary phase gas from top of the nitrogen washing tower top and other high-pressure nitrogen such that the hydrogen and nitrogen ratio is 2.9-3.1, and reheating heat exchanger (H2) at -50 degrees C to -65 degrees C to form fresh air (A1), separating fresh gas into two fraction, introducing one fraction of fresh air into methane rectification tower, heating in a reboiler and cooling at -55 degrees C to -70 degrees C to obtain fresh air (A2), introducing secondary fresh air into low-temperature methanol washing process, and reheating at 25-35 degrees C to obtain fresh air (A3), reheating another fraction of fresh air (A3) through heat exchanger (H1) at 25-35 degrees C to form fresh air (A4), and mixing fresh air (A3) and fresh air (A4) to form ammonia gas mixture of fresh air which is introduced into ammonia synthesis section, introducing liquid phase (l1) raw material from bottom of the flash tank into upper portion of a methane rectification tower, reducing isenthalpic pressure to 0.25-0.35 MPa, introducing methane-rich liquid phase contained in the bottom of the methane rectification tower into heat exchanger (H2), reheating in heat exchanger (H1) at 35 degrees C and storing in a synthetic natural gas tank, reducing isenthalpic pressure of carbon monoxide-rich fraction in the bottom of the nitrogen washing tower to 0.25-0.35 MPa, and introducing into carbon monoxide-rich liquid tank, carrying out flash evaporation at -180 degrees C to -195 degrees C, introducing carbon monoxide-rich liquid into the condenser cooling end of the methane rectification tower, gasifying and condensing, mixing the fraction (i) and carbon-monoxide-rich liquid top flow of the air, and reheating by heat exchanger (H3) at -150 degrees C to -160 degrees C, mixing liquid phase in the condenser of the methane rectification tower top and gas phase, and heating in heat exchanger (H1) at 25-35 degrees C to form tail gas and passed into fuel gas pipeline network. An INDEPENDENT CLAIM is included for apparatus for purifying ammonia synthesis gas and co-generating synthetic natural gas and/or liquefied natural gas, which consists of heat exchanger (H1), heat exchanger (H2), heat exchanger (H3), nitrogen washing tower, methane rectification tower, condenser provided in the top of the methane rectification tower, reboiler provided in the bottom of the methane rectification tower, raw material flash tank, carbon monoxide-rich liquid tank and liquid methane pump.