TiO2 thin films were prepared by RF sputtering on Si wafer to investigate hydrophilicity and bactericidal effects by using AFM, XRD, standard plate count method and wetting angle measurement. Experimentally, the survival rate of E coli was above 74% and the wetting angle of water for the 30 min UV illuminated films was 4.2degrees. It was found that the bactericidal efficiency was closely related to the large specific surface area caused by the roughness, however, hydrophilicity was governed by the surface defective sites rather than the roughness.