CeO2 modification was carried out on V-W-Ti catalyst, and the denitration performance of the catalyst was tested with different levels of CeO2 addition. The results showed that the addition of CeO2 could improve the medium and low temperature activities of the catalyst significantly, but too much loading would reduce the high temperature activity of the catalyst. Overall, V-W-Ti catalyst containing 1% of CeO2 in the mass of the catalyst showed the best performance. Its denitrification activity was better than that of the unmodified catalyst across the entire temperature range. Under reaction conditions of 260 ℃ and GHSV of 60000 h-1, its NOx removal efficiency increased from 79.01% to 99.19%. In an atmosphere containing H2O and SO2, its NOx removal efficiency increased from 58.33% to 74.55%. The catalyst with different CeO2 additions were characterized by XRD, N2 adsorption-desorption, XPS, NH3 temperature programmed desorption (NH3-TPD), and FTIR, which showed that the CeO2 addition increased the proportion of adsorbed oxygen and Br?nsted acidic sites on the catalyst surface , but it also decreased the proportion of V4+ and Lewis acidic sites on the surface, so CeO2 addition has different effects on the denitrification activity of V-W-Ti catalyst at low and high temperatures. DFT calculation results show that Ce doping reduces the formation energy for the oxygen vacancy on the catalyst surface, changes the acidity of the catalyst surface and enhances the adsorption of SO2 on the catalyst.