In this paper, by controlling the calcination temperature, ordered mesoporous Al₂O₃ with controllable pore diameters were rationally designed and synthesized by evaporation-induced self-assembly method. The CuMn-Al₂O₃ catalysts with different pores were synthesized by a co-impregnation method with ordered mesoporous Al₂O₃ as template. These catalysts expressed ordered mesoporous structure, possessed higher specific surface area and large pore volume, and owned more surface active sites, which were helpful for CO oxidation. When the calcination temperature of Al₂O₃ was 400 ℃, this catalyst showed the highest catalytic activity. The reason was due to its relatively stronger redox ability and surface activity species. More Cu⁺ and chemisorbed oxygen concentration was very useful in achieving the highest catalytic performance.