Abstract: The α-chloropropionic acid was synthesised by propionic acid using propionic anhydride as catalyst,chlorine as chlorinating agent.The effect of temperature and amount of catalyst was investigated on the yield of product.The optimal conditions were determined to be temperature 130 ℃,n(propionic anhydride):n(propionic acid)=1∶6,chlorine mass flow 90 mL/min and air feed 15 mL/min.The product purity reached 96% and the yield reached 89%.The kintics curves were drawn and the reaction mechanism was studied preliminarily.