The invention discloses a N-sulfonyl substituted tetrahydroisoquinoline derivatives and a preparation method thereof. According to the method, the reaction between substituted benzyl alcohol and substituted sulfonyl-ethylene imine is catalyzed by using trifluoro-sulfonate to synthesize N-sulfonyl replaced tetrahydroisoquinoline derivatives. Compared with the prior art, the preparation method comprises the advantages that less reaction steps and high yield since the N-sulfonyl replaced tetrahydroisoquinoline derivatives are prepared by a series of ring opening-cyclizing reactions of the substituted sulfonyl-ethylene imine by using the substituted benzyl alcohol.