The invention specifically relates to a nanometer copper-cerium composite oxide catalyst, and a preparation method and application thereof, belonging to the technical field of chemical catalysts. The invention provides application application the nanometer copper-cerium composite oxide catalyst in purification of circulation gas during production of glyoxal through atmospheric oxidation of glycol. According to the invention, nitrates or acetates of copper and cerium are mixed and then dissolved in absolute ethyl alcohol; then epoxypropane is added so as to form gel; and then heat treatment is carried out in an inert atmosphere and air atmosphere respectively so as to prepare the nanometer copper-cerium composite oxide catalyst. The catalyst prepared in the invention has good activity and stability and can be used for purification of circulation gas during production of glyoxal through atmospheric oxidation of glycol; and under the working conditions of production of glyoxal through atmospheric oxidation of glycol, the catalyst allows organic matters in the circulation gas to be completely oxidized, so the purpose of purifying the circulation gas is achieved.