The invention discloses a synthesis method of alpha-chloropropionyl chloride. The synthesis method comprises the following steps: (1) adding propionic acid, an acyl chloride catalyst and solvent into a reactor, starting to stir, introducing chlorine gas to perform substitution reaction, and distilling to collect an alpha-chloropropionic acid fraction directly used for next step of reaction after the reaction is completed; and (2) adding the alpha-chloropropionic acid obtained in the previous step and a catalyst into the reactor, starting to stir, slowly heating, introducing phosgene to react, and performing reduced pressure distillation after the reaction is completed to obtain the alpha-chloropropionyl chloride. The preparation method disclosed by the invention has the advantages of simple operation, high yield, no wastewater production during aftertreatment, mild reaction conditions and the like; and the acyl chloride catalyst used in the chlorination reaction of the first step can be recycled.