The physical properties which affect on the activity of photocatalysts are active site number and surface area, etc. Recently, to control these properties, 'Sol-Gel' methods are used to synthesize photocatalysts. In this study, we synthesized spherical TiO₂-SiO₂ photocatalysts by mixed solvent method, and analyzed the changes in morphology of the catalysts with synthesis conditions by SEM and the changes in physical properties of the particles and the variation of the crystal structure with Ti concentration and calcination temperature by TGA, BET, FT-IR and XRD. Then we investigated the effects of the physical properties and [Ti]/[Si] ratio on photocatalytic degradation of iso-propanol. The particle size was decreased with increasing HPC concentration and decreasing Ti concentration. The surface area of the catalysts was decreased by increasing Ti concentration and calcination temperature. As Ti concentration was increased, Ti-O-Si bond number was increased, and by calcination, the number was increased until 400℃, then decreased with increasing calcination temperature. The extent of photodegradation of isopropanol was higher as photocatalysts have more Ti, but the turnover frequency of the Ti was higher as the catalysts have less Ti. Because (Ti³⁺-O^-)^* number and the surface area of the photocatalysts are decreased by increasing calcination temperature, the photodegradation of organic material is decreased.