An alignment film coating machine and a coating method are provided. The alignment film coating machine includes an equipment for carrying a substrate, a spray head for spraying PI droplets, and an air knife disposed on the equipment and located on one side of the spray head. The air knife is used for moving along the equipment and blowing uniform impact air curtain to the PI droplets after the spray head sprays the PI droplets on the substrate. By adding the air knife into the alignment film coating machine, the diffusion ability of the PI droplets is improved due to the uniform impact air curtain blown by the air knife. The resistance in diffusion is overcome. The PI droplets enter the via hole. Mura, which is induced by a relatively thicker PI film around the via hole as a result of the accumulation of the PI droplets, is prevented.