The preparation of silica antireflective coating through sol- gel process is discussed involving the composition of coating solution, cleaning of substrate and coating process. The porous silica film can be deposited on the silica lens by dipping from the solution, with the base catalyzed hydrolyzation of tetraeathyl silicate (TEOS) in anhydrous ethyl alcohol. The transmission of coating on the silica lens is 98.3 % at 350nm, and the peak transmission is over 99.0%.