The invention discloses a synthesis method of an amidine compound. The synthesis method comprises the following step of, in an oxygen-containing atmosphere and an organic carboxylate /polar aprotic solvent mixed system, performing reaction on arylmethyl ketone or aromatic heterocyclic methyl ketone and primary amine under catalysis of a copper salt and/or a cuprous salt, or performing reaction onthe arylmethyl ketone or the aromatic heterocyclic methyl ketone, the primary amine and secondary amine under catalysis of the copper salt and/or the cuprous salt to obtain the amidine compound. For producing the amidine compound with one-step reaction by taking the arylmethyl ketone or the aromatic heterocyclic methyl ketone and an amine compound as raw materials, the method has the characteristics of simple steps, low cost and the like and is beneficial to industrial production.