The invention provides a method for purifying 4, 6-dichloro pyrimidine. The method comprises the following steps of providing a reaction mixture comprising the 4, 6-dichloro pyrimidine prepared through a phosphorus oxychloride chlorination process; after cooling the reaction mixture comprising the 4, 6-dichloro pyrimidine, mixing the reaction mixture comprising the 4, 6-dichloro pyrimidine with an organic solvent, and extracting so as to obtain an organic phase; after washing, dehydrating and concentrating the organic phase, cooling and crystallizing, thus obtaining pure 4, 6-dichloro pyrimidine. According to the method, firstly, the reaction mixture comprising the 4, 6-dichloro pyrimidine is extracted by the organic solvent, the phosphorus oxychloride and dichloro phosphoric acid in the reaction mixture is prevented from being contacted with water, so that the operation is easy to control, and the safety is good. After extraction, the catalyst and phosphorus containing by-products are not damaged and can be recycled, so that the phosphorus containing by-products are possible to be used comprehensively, and the environment is prevented from being contaminated. Furthermore, the method has high product yield. Experiment results show that the yield of the 4, 6-dichloro pyrimidine is over 94%.