The invention belongs to the field of chemically synthesized food additives and particularly relates to a refining method of Neotame, namely a method for removing impurities N-[N-(3,3-dimethyl butyl)-L-alpha-aspartyl]-L-phenylalanine (impurities A) generated by hydrolysis of N-[N-(3,3-dimethyl butyl)-L-alpha-aspartyl]-L-phenylalanine-1-methyl ester (Neotame). The refining method of the Neotame ischaracterized by comprising the following steps: performing heating and dissolved clarification on the Neotame containing the hydrolyzed impurities A in a methanol and water mixed solvent, adding sodium hydrogen carbonate to perform treatment and performing crystallization to obtain products so as to effectively remove the impurities A. The refining method of the Neotame has the following beneficial effects: the Neotame refined product is obtained by refining the Neotame, and the refining yield is more than 90 percent. The liquid phase purity of the refined Neotame can reach to more than 99.9percent, and the impurities A are reduced to be within 0.1 percent, so that the quality of the Neotame in production is improved, and the quality safety requirements of medicine product auxiliary materials and food additives are further improved and met.