The invention relates to a method for recovering petrochemical engineering output gases with advantages of strong applicability, low energy consumption and high product purity. The method has excellent wide applicability, is applicable to gas by-products produced in petrochemical processing procedures such as catalytic cracking, pyrolysis, catalytic reforming, isomerization and the like, and realizes high-efficiency recovery of hydrogen, carbon monoxide, methane, ethylene, ethane and the like in chemical gases. Moreover, absorbents and refrigerants are recycled, and the economic value is high.