The invention discloses a method for preparing a nano 
titanium dioxide 
coating on the surface of a base material made of transparent glass and 
polymer. The method is characterized by comprising the following steps: taking TiCl4 as the 
titanium source to obtain a precursor reaction fluid, using a rotation 
coating instrument to paint 10 to 20 [mu]L of the precursor reaction fluid on a substrate, which has been subjected to a pretreatment, so as to obtain a uniform liquid membrane on the substrate; covering a BOPP film on the substrate, subjecting the substrate to light 
radiation in an 
ultraviolet lamp cabinet, taking out the substrate after 5 to 10 minutes, removing the BOPP film, washing the substrate, and finally 
drying so as to obtain the transparent TiO2 
surface coating. If an 
ethyl stearate solution is painted on the 
substrate surface before the precursor reaction liquid is spin-painted on the substrate, and the post operations are not changed, a porous transparent TiO2 
coating will be formed on the 
substrate surface. The precursor reaction fluid is prepared by the following steps: taking TiCl4 as the 
titanium source, and then orderly adding TiCl4 and H2O2 into an acidic water solution of HNO3 under stirring. The provided TiO2 film is composed of pure 
anatase crystalline phase having a high photocatalytic activity, and the 
surface structure of the TiO2 film is controllable. The technology is simple, the used facilities are convenient and easily available, the film-forming speed is fast, the post-treatment is convenient, and the reaction mediums are nontoxic and harmless.