Nano anatase TiO2 thin films on glass slide substrates were prepared via a dip-coating method using refluxed sols (RS) as precursors, then dried under infrared light and calcined at 500°C for 30min. The RS sols and TiO2 films were characterized by FT-IR, XRD, TEM, UV-Vis and SEM. The photocatalytic activities of the film samples were tested by the degradation of methyl orange solution with a concentration of 10mg/L under UV light irradiation. The results reveal that the RS sols are flavescent, alkalescent and contain needle-like anatase crystals. The TiO2 films are uniform, compact and transparent, their maximal light transmittance exceed 80% under visible light region. The degradation of methyl orange results illustrate that the RS-6 TiO2 thin films show the best photocatalytic activities, the decoloration rate of the methyl orange solution with RS-6 TiO2 thin films reachs 99% after irradiated 160min under UV light.