TiO2　and　SO2-4/TiO2　photocatalysts　were　prepared　by　sol-gel　method　and　characterized　by　X-ray　diffraction　(XRD),　BET　N2　sorption　analysis,　IR　spectroscopy　and　UV-Vis　Diffuse　Reflectance　Spectroscopy　(DRS).　Photocatalytic　degradation　of　CH3Br　in　air　stream　was　studied　over　TiO2　and　SO2-4/TiO2　catalysts　under　various　reaction　conditions.　The　results　indicated　that　the　structural　and　photocatalytic　properties　of　TiO2　were　greatly　improved　by　sulfation.　The　sulfated　TiO2　(SO2-4/TiO2)　showed　excellent　reaction　activity　and　stability　for　CH3Br　photocatalytic　decomposition　even　under　the　moist　reaction　conditions.　It　was　found　that　both　B　acid　sites　and　L　acid　sites　exist　on　the　SO2-4/TiO2　catalyst,　forming　cooperative　centers　with　superacidic　characteristics.　When　compared　to　unmodified　TiO2,　the　SO2-4/TiO2　catalyst　exhibited　higher　anatase　content,　smaller　crystal　size,　higher　specific　surface　area,　centralized　pore　size　distribution,　and　the　blue-shifted　band　edge　of　Uv-vis　adsorption　spectra.