The invention discloses a process for efficiently converting green electricity into low-energy-consumption air separation energy storage and purifying and liquefying CO2. The required device comprises a filter, an air compressor, an air pre-cooling system, a molecular sieve adsorber, an electric heater, a main heat exchanger, rectifying towers I and II, main condensation evaporators I, II, III and IV, subcoolers I and II, a high-temperature expansion machine, a low-temperature expansion machine, a low-temperature refrigerator, a liquid nitrogen pump I, a circulating nitrogen compressor, a water cooler behind the circulating nitrogen compressor, a liquid nitrogen storage tank, a CO2 rectifying tower, a CO2 supercharger and a liquid CO2 storage tank, wherein the molecular sieve adsorber, the electric heater, the main heat exchanger, the rectifying towers I and II, the main condensation evaporators I, II, III and IV are alternately used. According to the invention, medium and high pressure nitrogen, high purity rich oxygen and liquid nitrogen are prepared by using green electricity, CO2 enriched and purified by a circulating flue gas purification system is purified and liquefied to prepare gaseous and liquid CO2 products, the medium and high pressure nitrogen and the gaseous CO2 products are subjected to oil displacement in an oil well, the green electricity is stored in a liquid form by the liquid nitrogen and the liquid CO2 products, and the green electricity is subjected to oil displacement in the oil well and/or expansion power generation after being pressurized and vaporized. And efficient conversion and utilization of green electricity are realized.