The invention discloses a combined power circulating method capable of catching carbon dioxide (CO2) by using LNG (Liquefied Natural Gas) cold energy and a system thereof. The system comprises an air separation device, an oxygen-enriched-combustion gas turbine circulation device, a high-pressure steam power circulation device, a CO2 separation and liquefaction device and an LNG cold energy power circulation device, wherein the air separation device, the oxygen-enriched-combustion gas turbine circulation device, the high-pressure steam power circulation device, the CO2 separation and liquefaction device and the LNG cold energy power circulation device utilize the LNG cold energy. According to the method and the system, electricity and high-temperature fume which is rich in CO2 and water are generated from LNG through the oxygen-enriched-combustion gas turbine circulation device, and heat is recovered from the fume through the high-pressure steam power circulation device, so as to produce high-temperature and high-pressure steam with the pressure over 18MPa and increase the power generation efficiency of natural gas; moreover, the LNG cold energy is sequentially applied to the air separation device, the LNG cold energy power circulation device and the CO2 separation and liquefaction device, and the energy consumption for CO2 catching is lowered by making full use of the LNG cold energy, so that combined power cycle has relatively high power generation efficiency and relatively high CO2 catching rate, and the efficient utilization of the LNG cold energy is realized.