Using 4-benzyl-2-hydroxy-3-one as a starting material, a diastereoisomers of 4-b-enzyl-2-((R)-1-(3,5-bis(trifluoromethyl)phenyl)ethoxy)morpholin-3-one was prepared by two-st-ep reaction. Then the dynamic kinetic resolution of its asymmetric transformation was use-d to convert it into chiral pure (R)-4-benzyl-2-((R)-1-(3,5-bis(trifluoromethyl)phenyl)ethoxy)morpholin-3-one under potassium t-butoxide as the alkaline conditions. The ratio of the co-nverted chiral product and diastereomer is 96:4, which has greatly utility value in the pro-cess of the industrial preparation of neural excitation peptide 1 (NK-1) receptor blockers(Aprepitant).