The　differences　of　spectral　behavior　between　SO2-　4/TiO2　and　TiO2　photocatalysts　were　studied　by　using　IR　Raman　as　well　as　UV-Vis　diffuse　reflectance　spectroscopy(DRS).　The　results　showed　that　both　L　and　B　acid　sites　exist　on　SO2-　4/TiO2　photocatalyst　while　only　L　acid　sites　on　TiO2　photocatalyst.　As　compared　with　unmodified　TiO2,　the　sulfated　TiO2(SO2-　4/TiO2)　exhibits　higher　resistance　to　crystal　phase　transition　from　anatase　to　rutile,　higher　resistance　to　growth　of　crystal　grain.　As　the　results　of　sulfation,　SO2-　4/　TiO2　samples　possess　higher　anatase　content,　smaller　crystal　grain,　and　the　blue-shifted　band　edge　of　adsorption　spectra,　which　increases　the　optical　absorption　threshold　value　and　yield　larger　redox　potential.