The invention relates to a preparation method of N-phenylmethyl benzylamine, which is characterized by comprising the following steps of by using polyoxometallate as a catalyst, putting into a reaction container, sequentially adding an organic solvent, benzylamine and benzoic acid into the container, finally adding an additive, heating, stirring, reacting, and separating to obtain the N-phenylmethyl benzylamine. After the reaction is finished, the catalyst can be recycled, the system after the reaction is finished is directly filtered, the polyoxometallate can be directly filtered out and recycled after being treated, and the recycled polyacid is used for preparing the N-phenylmethyl benzylamine. Compared with the prior art, the method has the advantages that benzylammonium and benzoic acid can react to prepare N-phenylmethyl benzylamine, high activity and high selectivity are achieved, reaction conditions are mild, environment friendliness is achieved, the catalyst can be recycled, and great industrial production potential is achieved.