The purpose of this study is to investigate the interaction of Ce and W species with TiO₂, Al₂O₃ and SiO₂ supports, so as to illustrate the influence of supports and distribution of Ce, W species on SCR reaction. It is found that low-temperature activity followed the order of CeW > CeWTi > CeWAl > CeWSi. The reasons for the various activity of the catalyst were investigated by a series of characterization. The low-temperature NH₃-SCR activity is associated with the surface concentrations of Ce³⁺, oxygen vacancies and active oxygen species, which are dominated by the dispersion and interactions of Ce/W species with the supports. Arising from interactions of Ti⁴⁺ with high-density electron cloud, finely dispersed Ce and W species facilitate the W-Ce synergism and produce more active oxygen. All these contribute toTiO₂ can make Ce and W species in an ideal distribution, so the corresponding catalyst shows excellent NO_x conversion of CeWTi catalyst at 200–350 °C. The reaction process observed by in situ DRIFT indicated that the NH₃-SCR reaction on CeO₂-WO₃ containing catalysts mainly follow Langmuir-Hinshelwood (L-H) mechanism at low temperature. Based on the analysis of the characterization and reaction process, it is concluded that the control step of NH₃-SCR reaction at low temperature over CeO₂-WO₃ containing catalysts is the adsorption and activation of NO_x.