The invention relates to a novel preparation method for a hindered phenol antioxidant. The problems of multiple reaction steps, lower product yield, high environmental protection pressure and the like in the prior art are solved. According to the method, ester with a hindered phenol structure and hydrazine hydrate or diamine such as ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, pentamethylenediamine or hexanediamine serve as raw materials, a one-step method is adopted for synthesizing a target product, and an alkaline catalyst is added to facilitate reaction. The product is widely applied to electric wires, cables and products embedded with metal parts.