The invention discloses a high-activity and high-stability supported nanometer gold catalyst, preparation and an application method. An active component is Au, and a carrier is M1M2O-MOx composite oxides, wherein M1 is one or two or more of Mg, Cu, Ni and Zn, M2 is one or two or more of Al, Fe and Co, and MOx is one of Al2O3, TiO2 and SiO2. The M1M2O-MOx is prepared by adopting an impregnation method or a solution combustion method, metal M1 and M2 salts are introduced and calcinated under the temperature of 700-1200 DEG C so that M1 and M2 can generate a spinel or perovskite structure on the surface of the MOx oxides, the gold catalyst supported by the M1M2O-MOx has the advantages that the preparation process is simple, large-scale production is easy, the catalytic activity is high, and the reaction stability performance is excellent, 1% CO in air can be completely oxidized under the temperature of minus 40-50 DEG C to produce CO2, and the wide application prospect is achieved in CO2 reduction of a closed CO2 laser and air purification of the environment such as a mine self-rescuer, a safety rescue capsule, a high-rise building, a tunnel, a closed place, a submarine and a space station.