The present invention discloses an intermediate for preparing N-cyclopropyl-(2S, 3S)-3-amino-2-hydroxy caproamide, a preparation method and applications thereof, wherein the intermediate has a chemical structure general formula represented by a formula I, R is a C1-C4 alkyl or aryl substituted C1-C4 alkyl, and 3-propyl ethylene oxide-2-formic acid and alkyl nitrile or aryl nitrile react in the presence of a Lewis acid so as to prepare the intermediate. With application of the intermediate of the present invention to prepare N-cyclopropyl-(2S, 3S)-3-amino-2-hydroxy caproamide, advantages of high yield, simple process, no requirement of any toxic reagents and special equipment, cheap and easily-available raw materials and the like are provided, the chiral purity of the obtained target product is greater than 99%, and the method is suitable for large-scale production and has industrial application values.