A MnO_x/γ-Al₂O₃ catalyst was prepared by impregnation of manganese acetate and alumina. After optimizing the composition, it was loaded into a ceramic filter (CF) by a one-step coating method. The results show that MnO_x/γ-Al₂O₃ had the best denitration activity when the Mn loading was 4 wt% with a calcination temperature of 400 °C. The MnO_x/γ-Al₂O₃ catalyst ceramic filter (MA-CCF) was made by loading the CF twice with MnO_x/γ-Al₂O₃. When face velocity (FV) was 1 m min⁻¹, MA-CCF displayed more than 80% NO conversion at 125–375 °C and possessed a good resistance of H₂O and SO₂. The abundant surface adsorbed oxygen, dense membrane and high-density fiber structure on the outer layer of CF effectively protected the catalyst and could improve MA-CCF denitration activity. The multiple advantages of MA-CCF made it possible for good application prospects.