Abstract: Disclosed is a method of synthesizing an ?-amino acid derivative, where an azirine compound, used as raw material, is reacted with a sulfhydryl compound in a mixed system of an organic solvent and a buffer solution under the protection of nitrogen to produce the ?-amino acid derivative. In the reaction, the carbon-nitrogen double bond of the azirine compound is attacked by the sulfhydryl compound, so that the azirine compound is directly opened to form the ?-amino acid derivative of which the same carbon atom is added with two molecules of the sulfhydryl compound. This method can be performed directly in an aqueous phase without using a metal catalyst.