The invention discloses a preparation method of 5-benzyl benzydamine. According to the method, 4-bromo-2-nitrobenzoic acid is taken as a starting material, and 5-benzyl benzydamine is synthesized through ten steps of reactions. The optimal preparation steps and reaction conditions are screened out through large quantities of experiments, the reaction conditions are milder, and the operability is high. The purity of 5-benzyl benzydamine prepared with the method can be 98% or higher, 5-benzyl benzydamine provides important basis for scientific evaluation of the quality, safety and potency of benzydamine and has great significance in improvement of a synthesis process.