Abstract: To investigate the influence of pore structure on the catalytic activity of catalysts, four catalysts including three-dimensionally ordered macroporous-mesoporous (3DOM-m) CeTiO_x, three-dimensionally ordered macroporous (3DOM) CeTiO_x, three-dimensionally ordered mesoporous (3DOm) CeTiO_x and disordered mesoporous (DM) CeTiO_x were synthesized by the sol-gel method. The NH₃-SCR denitration testing results show that the performance of the catalysts with different pore structures follows the sequence of 3DOM-m CeTiO_x>3DOm CeTiO_x>3DOM CeTiO_x>DM CeTiO_x, and the 3DOM-m CeTiO_x shows an excellent catalytic activity, with more than 90% NO conversion in the range of 250–400 ℃ at a GHSV of 60000 h⁻¹ . The characterization of catalysts by XRD, SEM, BET, NH₃-TPD and in-situ DRIFTS indicates that the surface area is not the dominant factor determining the catalytic activity of CeTiO_x. 3DOM-m CeTiO_x has a highly ordered macroporous-mesoporous structure and abundant Bronsted acidic sites, thereby improving the denitrification activity. The NH₃-SCR reaction over the 3DOM-m CeTiO_x mainly follows the L-H and E-R mechanisms.