The invention provides a preparation method of polyvinyl alcohol collodion. The preparation method comprises the following steps: mixing polyvinyl alcohol with water, thus obtaining a polyvinyl alcohol aqueous solution; mixing the polyvinyl alcohol aqueous solution with a thickening agent, thus obtaining a thickening agent system; mixing the thickening agent system with a surfactant, thus obtaining a surfactant system; mixing the surfactant system with a catalyst, thus obtaining a catalyst system; mixing the catalyst system with a curing agent, thus obtaining injection molding liquid; and performing pouring and curing molding in sequence on the injection molding liquid, thus obtaining the polyvinyl alcohol collodion. According to the method provided by the invention, the speed increase of the viscosity of the injection molding liquid can be effectively controlled to ensure that the injection molding liquid is in a flowing state in an injection molding process to realize enlarged production; under enlargement of 45 times, 100 percent of injection molding can be realized; and moreover, the performance and the apparent appearance of a novel obtained product are equivalent to those of PVA (polyvinyl alcohol) collodion taking starch as a pore forming agent, so that the novel product can basically meet a production requirement.