The invention belongs to the technical field of paints, and relates to a polyvinyl alcohol fiber-fluorine polyurethane anti-cavitation paint and a preparation method thereof. The film forming material of the paint is fluorine-containing polyurethane, and has the advantages of high adhesive force, high toughness, weather resistance, chemical mediator resistance, temperature resistance, low surface energy, low friction property and the like. By adding the high-strength high-modulus polyvinyl alcohol fiber as the filler, the paint has the advantages of very high tensile strength and modulus, acid/alkali resistance, aging resistance, corrosion resistance, weather resistance and the like; and the effective combination of the filler and the paint film forming material can further enhance the properties of the coating. The isocyanate-grafted high-strength high-modulus polyvinyl alcohol fiber, which is prepared by carrying out grafting reaction on the hydroxyls on the surface of the high-strength high-modulus polyvinyl alcohol fiber and isocyanates, is used as the filler. The anti-cavitation coating prepared by applying the paint at normal temperature has the characteristics of easy production, simple application, light weight, erosion resistance, corrosion resistance and the like, and is mainly used for protecting propellers, pumps, valves, pipelines and the like in a cavitation environment.