The invention discloses a preparation method of a butyrolactone derivative. The preparation method includes the following steps that 1, a compound shown in the formula (II) is resolved with chiral phenylethylamine to obtain a compound shown in the formula (III); 2, the compound shown in the formula (III) is subjected to carboxyl reduction with borane to obtain a compound shown in the formula (IV);3, the compound shown in the formula (IV) is subjected to cyan-hydrolysis under the alkaline condition to obtain a carboxylic acid derivative shown in the formula (V), and a dehydration cyclization reaction is conducted to obtain the butyrolactone derivative shown in the formula (I). The new synthesis method of the butyrolactone derivative has the advantages that the cost of synthesis materials is low, only five reaction steps are needed, and thus the production cost can be obviously reduced. The synthesis route is shown in the description.