The invention belongs to the technical field of pharmaceutical chemistry synthesis, and relates to a preparation method of 5-(4-bromophenyl)-4,6-dichloropyrimidine. The preparation method comprises the following steps: carrying out catalytic esterification on bromophenylacetic acid to prepare methyl p-bromophenylacetate, then carrying out a reaction with dimethyl carbonate to synthesize 2-(4-bromophenyl)-malonic acid-1,3-diethyl ester, carrying out cyclization by using formamidine hydrochloride to obtain 5-(4-bromophenyl)-4,6-dihydroxy pyrimidine, and then carrying out chlorination to obtain the product 5-(4-bromophenyl)-4,6-dichloropyrimidine. In the preparation process of the intermediate 1, a solid acid is adopted as a catalyst, so that the synthesis process and a post-treatment step are simplified. The solid acid is easy to separate and can be repeatedly used, so that resources are saved, and production cost is reduced. In a process of preparing the intermediate 2, sodium methoxideis adopted as an alkali to replace sodium hydride or amino sodium used in the prior art, so that production safety is improved, and production cost is reduced. Meanwhile, the intermediate 3 is prepared by adopting a one-pot method, so that operation steps are reduced.