The invention relates to a preparation method of high-purity 1,4-dibromonaphthalene and belongs to the technical field of organic synthesis. The provided preparation method of high-purity 1,4-dibromonaphthalene aims to solve the problems that preparation methods of 1,4-dibromonaphthalene in the prior art are complicated, the reaction conditions are high, the product purity is low, the yield is low, and the product quality is unstable. The method comprises the four steps of a one-pot acetylation protection and selective bromination process, a hydrolysis deprotection process, a diazotization coupling reaction process and a recrystallization purification process to obtain high-purity 1,4-dibromonaphthalene. The provided preparation method has the advantages that the synthesis route is short,the reaction conditions are mild and easy to control, and the production cost is low. The organic synthesis reaction site is monotonous, the selectivity is high, the product purity is up to 99.0%, andthe total yield can reach 71.7%. Industrial production is easily realized, the need for large-scale production of 1,4-dibromonaphthalene can be effectively met, and the method has a broad applicationprospect.