The invention discloses a chemical synthesis method for optical pure R-2-hydroxyl-4-phenyl ethyl butyrate. The chemical synthesis method comprises the following steps: in an organic solvent and in the presence of azodiformate and triphenylphosphine, S-2-hydroxyl-4-phenyl ethyl butyrate and paranitrobenzoic acid are reacted and then filtered; after the filtrate is condensed and the solvent is recycled, R-esterified intermediate is obtained by recrystallization; the intermediate is catalyzed in ethanol by potassium carbonate to be subjected to transesterification reaction and then filtered; thefiltrate is neutralized by hydrochloric acid; after the solvent is recycled, the filtrate is extracted by ethylene dichloride which is then recycled by an organic phase; and the filtrate is distilledunder reduced pressure to obtain the optical pure R-2-hydroxyl-4-phenyl ethyl butyrate with high yield. The synthesis method for the R-2-hydroxyl-4-phenyl ethyl butyrate has the advantages of safety,high efficiency, quick and convenient operation, high selectivity, good yield and low cost, simplicity, general use and suitability for industrialized production.