Fe-based catalysts have a great potential to be used for selective catalytic reduction (SCR) of NOx with NH3 reaction due to their low cost, nontoxicity and excellent catalytic activity. The aim of this paper is to investigate Ce doping effect on activity of NH3-SCR over the FeOx/TiO2 catalyst. In-situ diffuse reflectance infrared fourier transform (DRIFT) technology was utilized to verify the adsorbed species on the surface of FeOx/TiO2 and FeOx-CeO2/TiO2 catalysts. With respect to the obtained results, among the four catalysts studied, the FeOx-CeO2/TiO2 with the FeOx/CeO2 ratio of 3/8 shows the best NO conversion more than 98％in the temperature range of 230-350 ℃. The active centers for NH3 adsorption and activation are assigned to Lewis acid sites over the FeOx-CeO2/TiO2 and monodentate nitrates can act as the key in-termediate in the NH3-SCR. Moreover, both of Langmuir-Hinshelwood and Eley-Rideal mechanisms are observed over the FeOx-CeO2/TiO2 catalysts in the SCR.