Abstract: Tripeptide L-prolyl-L-leucyl-glycinamide (PLG) has important physiological and pharmacological functions，and can be used to treat Parkinson’s disease. PLG was synthesized by using the mixed anhydride method from L-proline，L-leucine and glycinamide. The amino groups of L-proline and L-leucine were protected firstly by the carbobenzoxy group，and then the carbobenzoxy group was removed by Pd/C with H2 from L-cbz-prolyl-L-leulyl-gly -NH2 to produce PLG in the end. Isobutyl chloroformate was used as reagent to form mixed anhydride. The optimum conditions to synthesize L-cbz-pro and L-cbz-prolyl- L-leu，were n(cbz)/n(L-pro)=2.6:1 at －5 ℃ for 2 hours and n(i-C4H9OCOCl)/n (L-cbz-pro)=1:1 at －10 ℃ respectively. Under these conditions，the melting point，optical purity and total yield of PLG were 120～122 ℃，98.7% and 38.5% respectively. The specific rotation [α]D20 was －46.3°。