A film preparation system comprises a precursor solution preparation device and a film deposition device. The precursor solution preparation device comprises a liquid storage pot, a vaporization device and an absorption tower. The liquid storage pot and the vaporization device are communicated with the absorption tower. The liquid storage pot is used for storing coating film solution and providing the coating film solution to the absorption tower. The vaporization device is used for vaporizing dopant solution and providing the vaporized dopant solution to the absorption tower. The absorption tower is a plate-type absorption tower, a packed tower or a turbulent contact absorber. When the absorption tower is the plate-type absorption tower, a column plate of the plate-type absorption tower is a sieve pore column plate, a float valve column plate or a bubble-cap column plate. The absorption tower is used for ensuring the coating film solution to absorb the vaporized dopant solution so as to obtain the precursor solution. The film deposition device is used for introducing the precursor solution to the substrate surfaces to be subjected to film coating so as to form the film.