The invention discloses a preparation method of an N-substituted benzotriazole derivative. A structural formula of the N-substituted benzotriazole derivative is shown in the description. The preparation method of the derivative specifically comprises the following steps of uniformly mixing a benzotriazole derivative, an aniline derivative, an aldehyde compound, a catalyst and an organic solvent; performing condensation reaction at the temperature of 80 to 100 DEG C under the air atmosphere, so as to obtain the N-substituted benzotriazole derivative. The preparation method has the advantages that the N-substituted benzotriazole derivative which cannot be synthesized by other methods can be synthesized, and metal is not added; the obtaining of raw materials is easy, the yield is high, the reaction condition is mild, the reaction time is short, the primer range is wide, the reaction specificity is strong, the post-treatment is simple and convenient, and the green effect is realized.