TiO2　photocatalysts　prepared　by　sol-gel　method　were　characterized　by　X-ray　diffraction　(XRD),　UV　diffuse　reflectance　spectroscopy　(DRS),　N-2　adsorption　BET　method,　surface　photovoltage　spectroscopy　(SPS).　A　test　compound　ethylene　in　the　gas　phase　was　employed　in　the　heterogeneous　photocatalytic　oxidation　to　investigate　the　effects　of　properties　of　TiO2　nanoparticles　on　photocatalytic　performance.　The　results　showed　that　crystal　size　of　TiO2　increased　slowly　and　its　surface　area　downgraded　with　the　increasing　of　calcination　temperature;　the　crystal　phase　of　TiO2　changed　from　anatase　to　rutile,　the　threshold　of　SPS　decreased　and　the　band　edge　red-shifted　to　yield　smaller　redox　potential,　leading　to　the　significantly　decreased　of　photocatalytic　activity.