(S)-1-(2-chloroacetyl)pyrrolidine-2-carbonitrile was synthesized from L-proline via successive reactions with chloro-acetyl chloride，ammoniated by 1,1'-Carbonyldiimidazole with ammonium bicarbonate and dehydrated by phosphorus oxychloride;3-Aminoadamantanol was synthesized from 1-Adamantanamine hydrochloride by mixed acids, and then was replaced by alkali. This intermediate reacted with (S)-1-(2-chloroacetyl)pyrrolidine-2-carbonitrile to product the target compound vildagliptin. The Entire route is simple and easy to get raw materials, fewer steps, simple operation, mild reaction conditions. The total yield of vildagliptin was increased from 32% to 42%, purity more than 99%, The structure of product was characterized by IR, 1H NMR and MS.