Abstract: Nano TiO₂ sols are prepared by the sol-gel method,and high photocatalytic TiO₂ films are deposited by spin-coating technology. The effects of pH value,complexant and calcination temperature on the photocatalytic activity of TiO₂ films are studied in this paper. Complexant can effectively inhibit the hydrolysis rate of butyl titanate. The sols prepared by double-complexant have better stability and the corresponding films obtain higher photocatalytic activity. pH value can affect the hydrolysis rate of butyl titanate.Besides,it has a critical influence on the size of holes in the film surfaces. When pH value is 6,the film surface is covered with microNano holes. The calcination temperature determines the structure and size of TiO₂ particles,it also affects surface roughness and optical properties of TiO₂ films. The optimal process for preparing high photocatalytic TiO₂ films is firstly to prepare Nano TiO₂ sols with doublecomplexant and to adjust the p H of the sols to 6,followed by spin-coating with a spinning coater and calcination at 500 ℃ for 3 hours.