Y 2O 3/TiO 2 samples were prepared by sol-gel process and characterized by means of X-ray diffraction (XRD), laser Raman spectra (LRS), UV-visible diffuse reflectance spectra (DRS), specific surface area (BET), and transmission electron microscopy (TEM). The results show that the relative intensity of 101 peak of anatase and 002 peak of rutile, the mean crystal diameter and mean particle diameter of Y 2O 3/TiO 2 samples decrease while specific surface area increases owing to doping Y 2O 3. Y 2O 3/TiO 2 samples have a larger specific surface area and higher thermal stability. Owing to quantum size effect, the reflectance of Y 2O 3/TiO 2 samples is larger than that of pure TiO 2 in the range of 380～460 nm and the position of Raman peaks varies slightly. Being a model reaction, the photo-catalytic degradation of methylene blue (MB) with positive charge and methyl orange (MO) with negative charge was investigated in TiO 2 and Y 2O 3/TiO 2 nanopowder suspension irradiated by high-pressure mercury lamp. As a result, the addition of Y 2O 3 to TiO 2 is detrimental to photo-activity of TiO 2 for MB photo-degradation and photo-catalytic behavior is enhanced due to 5%, 10% Y 2O 3 deposited on TiO 2 for the photo-degradation of MO. And the relationship between photo-physical properties and photo-activity was discussed. Y 2 O 3 / TiO 2 samples were prepared by sol-gel process and characterized by means of X-ray diffraction (XRD), laser Raman spectra (LRS), UV-visible diffuse reflectance spectra , and transmission electron microscopy (TEM). The results show that the relative intensity of 101 peak of anatase and 002 peak of rutile, the mean crystal diameter and mean particle diameter of Y 2O 3 / TiO 2 samples decrease while specific surface area was created by Owing to quantum size effect, the reflectance of Y 2 O 3 / TiO 2 samples is larger than that of pure TiO 2 in the range of 380 ~ 460 nm and the position of Raman peaks varies slightly. Being a model reaction, the photo-catalytic degradation of methylene blue (MB) with positive charge and methyl orange (MO) with negative charge was investigated in TiO 2 and Y 2O 3 / TiO 2 nanopowder suspension irradiat ed by high-pressure mercury lamp. As a result, the addition of Y 2 O 3 to TiO 2 is detrimental to photo-activity of TiO 2 for MB photo-degradation and photo-catalytic behavior is enhanced due to 5%, 10% Y 2O 3 deposited on TiO 2 for the photo-degradation of MO. And the relationship between photo-physical properties and photo-activity was discussed.