The invention belongs to the field of antireflection polyester film research and particularly relates to a preparation method of an in-situ polymerized optical hybrid antireflection polyester film. Methyl methacrylate-grafted silica sol is synthesized and diluted and then coats the surface of the PET film in a spinning manner, so that the antireflection effect of the PET film is improved and the properties such as the hydrophobicity and the haze are changed.