The invention relates to a process and a matching system for separating carbonylation feed gas, which organically integrates low-temperature methanol washing, precision filter, pre-adsorption, CO cold box, CO compression, pressure swing adsorption hydrogen production, desorption gas compression, membrane separation, permeating gas compression and feed gas cooler units, combines the advantages of multiple separation technologies, effectively overcomes respective disadvantages and obviously improves the condensability and the recovery rate of effective gas of H2 and CO in the carbonylation feedgas under the premise of not increasing fixed equipment investment and operating cost. In the invention, the compressor power consumption is only 35% of that completely subject to the pressure swing adsorption technology, the occupied area is less than 15% of that completely subject to the pressure swing adsorption technology, and the total investment is less than 70% of that completely subject to the pressure swing adsorption technology. The invention is applicable to the separation of CO and H2 in coal gas, natural gas, light oil, pyrolysis gas, coke oven gas, calcium carbide tail gas, yellow phosphorus tail gas and other carbonylation feed gas.