The utility model discloses a device for purifying and liquefying CO2 in oxygen-enriched combustion flue gas and relates to an industrial waste gas recovering and treating device. The device comprises a feed-gas heat exchanging system, a product-gas compressing and cooling system and a waste gas emptying system, wherein the feed-gas heat exchanging system comprises a CO2 flue gas heat exchanger, a CO2 flue gas primary separator, and a CO2 flue gas secondary separator; a feed-gas CO2 flue gas channel of the CO2 flue gas heat exchanger is communicated with an inlet of the CO2 flue gas primary separator; two product-gas outlets of the CO2 flue gas heat exchanger are respectively communicated with the product-gas compressing and cooling system; a secondary separation gas phase returning channel outlet of the CO2 flue gas heat exchanger is communicated with the waste gas emptying system. The utility model provides a system for purifying and liquefying CO2 in oxygen-enriched combustion flue gas which is relatively simple in structure, has high recovering rate for the low-concentration CO2 feed gas (the CO2 concentration is about 80%), and is suitable for industrial application on a large scale.