Objective:To synthesize optic pure L-norvaline. Methods: L-Norvaline was synthesized using n-butyraldehyde and potassium cyanide as starting material and (S)-(-)-α-methylbenzylamine as a chiral auxiliary agent by a selective Strecker reaction. Nearly optical pure α-amino nitrile was obtained by recrystallization; L-Norvaline was then obtained by hydrolysis and catalyzed debenzylation of α-amino nitrile. Results: The optimized reaction solvent system was chosen and high optical pure L-Norvaline was obtained by twice recrystallization procedure. Conclusion: Our method has less steps and is more selective than conventional methods and has a higher yield (47.4%).