The invention discloses a preparation method for nebracetam, and belongs to the technical field of medical chemistry. The key points of the technical scheme of the invention are as follows: the preparation method for the nebracetam comprises the following steps: performing Michael addition reaction and intramolecular cyclization on dimethyl itaconate and benzylamine serving as raw materials to obtain 1-benzyl-5-oxopyrrolidin-3-carboxylic methyl ester; reducing the 1-benzyl-5-oxopyrrolidin-3-carboxylic methyl ester by sodium borohydride to obtain 1-benzyl-4-hydroxymethyl-pyrrolidine-2-keton; performing methyl sulfonylation on the 1-benzyl-4-hydroxymethyl-pyrrolidine-2-keton to obtain 1-benzyl-5-oxopyrrolidin-3-carboxylic methanesulfonate; finally, performing ammonification and reduction on the 1-benzyl-5-oxopyrrolidin-3-carboxylic methanesulfonate by using ammonia water to obtain the nebracetam. The preparation method is simple in preparation process, easy to control and high in target product yield, and meets the requirement for green chemistry.