Abstract: MnO_x-MoO₃/TiO₂-Al₂O₃（MMTA） catalysts with various loads of Mn and Mo were prepared by dipping method,and its catalytic activity was studied in the selective catalytic reduction of NO with NH₃（NH₃-SCR）.The effects of temperature and different carrier on the SCR reaction were evaluated in the fixed bed continuous reactor.The catalyst was characterized by X-ray diffraction（XRD）,scanning electron microscope（SEM） and BET to observe its crystal phase and micro-morphology.The results indicate that,compared to the catalysts supported by TiO₂（T）,the catalysts supported by TiO₂-Al₂O₃（TA） have larger specific surface area and pore volume,which are favorable to decentralize active component MnO_x.Meanwhile,MnO_x-MoO₃/TiO₂-Al₂O₃（MMTA） catalysts exhibit good catalytic activity and excellent stability at high temperature.The NO_x conversion ranges from 75% to 95% at 150 ℃ to 450 ℃ and airspeed of 10 000 h^-1.Thus,the emissions of nitrogen oxides can be controlled effectively.The products show great application potential.