In order to overcome the shortcomings of the prior art, the invention provides a method for preparing a toluene benzyl phenyl substituted compound. According to the method, first a reaction substrateand an attack reagent are added in a reaction vessel and mixed; a catalyst is added to the mixture and evenly mixed; the evenly mixed material reacts for 12-48 h at 70-110 DEG C; finally, a solvent isremoved, and a product is purified, to obtain the toluene benzyl substituted compound. The reaction substrate is a compound containing a phenyl group and having at least one alpha hydrogen attached to the phenyl group; and the attack reagent is phenylboronic acid. The catalyst is a mixture of di-tert-butyl peroxide and nickel acetylacetonate. By synthesizing 2 kg of diphenhydramine hydrochloridethrough the synthetic method, the cost can be reduced by 150000 yuan.