Abstract: The preparation of SiO2 colloids by alkali-catalyze method was reported. The single film of SiO2 was prepared by dip coating method on K9 glass. After the films being treated in different ways, including heat, UV irradiation, ammonia and hexamethyl disilazane, and acid film coating treatments, the properties of the films were analyzed by spectrophotometry, Fourier transform infrared spectroscopy, scanning probe microscope, contact angle measuring apparatus and spectroscopic ellipsometer, et al. The contamination resist capabilities of the single film before and after accelerated contamination in vacuum were compared. The results indicate that the transmittance of the complex film with an acid film is still above 99%, and the water contact angle is 128°, the contamination resistant capabil