Sintering flue gas is faced with serious denitrification pressure, traditional vanadium tungsten titanium catalyst can effectively remove nitrogen oxides in industrial flue gas above 280℃, which is 100~150℃ higher than that of sintering flue gas. The purpose of denitrification can be achieved by heating sintering flue gas, but it will undoubtedly cause huge energy consumption, which is inconsistent with the concept of carbon emission reduction proposed by China. Therefore, it is necessary to develop denitrification catalysts with low-temperature activity. At present, the CeMn-based catalyst can achieve efficient denitrification in the sintering flue gas temperature range and has broad application prospects. In this study, the Ti/Sn doped CeMn composite metal oxide catalysts were prepared by a coprecipitation method. The effect of Ti/Sn modification on the denitrification and water resistance of the CeMnOx catalyst was studied. The microstructure, ammonia adsorption state, redox capacity, and surface element valence of CeMnOx catalyst were analyzed by physical and chemical properties characterization. The results showed that both Ti and Sn elements improve the low-temperature NOx conversion activity and water resistance of CeMnOx catalyst, and Ti presented a more significant improvement effect. At 150~250℃, the denitrification efficiency of CeMnTiOx was close to 100%. When the reaction temperature was 200℃ and the mixed gas contained 10vol% H2O, the denitrification efficiency of the catalyst remained above 95%. The results of H2 temperature programmed reduction, NH3 temperature programmed desorption, and X-ray photoelectron spectroscopy showed that the Ce-O-Ti and Mn-O-Ti structures in the modified catalyst improve the redox performance of the catalyst, increase the number of weak acid sites and medium strong acid sites on the surface of the catalyst, and form more oxygen vacancies, which made the catalyst exhibit better low-temperature activity.