The invention relates to a method for preparing a plastic scintillator thin film. The method comprises the steps that a plastic scintillation block body is dissolved in toluene under the room temperature condition, then is stirred until the plastic scintillation block body is completely dissolved, and is allowed to stand for 12-24 hours in a sealing mode; a substrate is cleaned; and one end of thecleaned substrate is clamped by a lifting machine and the cleaned substrate is kept vertical, meanwhile, a beaker provided with the plastic scintillator solution is placed under the substrate, the substrate is enabled to be immersed in the solution for impregnation, then the substrate is slowly lifted out of the solution, a layer of wet film is formed on the surface of the substrate after the substrate is completely separated from the solution, the substrate is kept to stand still to allow the toluene to be volatilized to enable the thin film to be preliminarily cured, the above steps are repeated to enable the substrate to be obliquely placed in a drying environment for 3-4 days in a mode of being away from the light, the toluene solvent in the thin film is cured after being completely volatilized, an opening is scraped along the edge of the thin film to enable the thin film to be separated from the substrate, and the plastic scintillator thin film is prepared and obtained. Comparedwith the prior art, the plastic scintillator thin film with the self-supporting thickness of 10-200 microns can be prepared through the method.