Abstract: Using tetraethoxylsilane as precursor and ammonia as catalyst, the fluoroalkylsilane was doped when the silica sol was growing, and the fluorin-doped silica antireflective coating was prepared by sol-gel process on K9 substrate. The properties of the coatings with and without fluorin were characterized with infared spectrometer, spectrophotometer, atomic force microscope, ellipsometer, contact angle measurement and N2-adsorption/desorption analysis. The results indicate that the peak transmittance of the fluorin-doped coating is 99.7%, and its water contact angle and polydimethyl siloxane oil contact angle are 129° and 86°, respectively. The contamination-resistant capability of the fluorin-doped antireflective coating is much better than the common one．