The invention relates to a method for preparing a-fluoro-propionyl acetate. The method comprises the following steps: 1) reacting propionyl acetate with sulfuryl chloride to generate a-chloro-propionyl acetate; 2) at the presence of polyethylene glycol and a polar aprotic solvent, substituting chlorinum in a-chloro-propionyl acetate with a fluorinating agent to obtain a-fluoro-propionyl acetate. Potassium fluoride or sodium fluoride is optimally used as the fluorinating agent, and polyethylene glycol 400, polyethylene glycol 600, polyethylene glycol 800 and polyethylene glycol 1000 can be used as the polyethylene glycol, wherein the polyethylene glycol is optimally the polyethylene glycol 800. The method has the advantages that the production process is safe, reaction conditions are mild, and meanwhile, the product yield is increased.