Abstract: TiO2-SiO2 mixed oxides (TS) were prepared under different pH values by co-precipitation method and characterized by means of N2-physisortion，X-ray diffraction，temperature-programmed desorption and infrared spectroscopy. With these TS oxides as carrier and CuO, Cr2O3 and CeO2 as the active components, Cu-Cr-Ce/TS catalysts were prepared and their catalytic performance for the selective reduction of NO by NH3 was investigated between 140 ℃and 220 ℃. Results showed the Cu-Cr-Ce/TS catalyst，in which the TS was prepared under pH values between 10 and 11，appears to have the highest catalytic activity under lower temperature. This is due to the larger specific surface area and the more weak acid center of the TS support，through which a large number of NH3 molecules can be adsorbed as to react easily with NO.