The invention discloses a preparation method of 4,6-dichloropyrimidine. The preparation method comprises the following steps: 1) mixing 4,6-dyhydroxy
pyrimidine,
phosphorus oxychloride and
phosphorus pentachloride, controlling the temperature to be 50-110 DEG C, reacting, stopping the reaction until the content of 4,6-dyhydroxy
pyrimidine is lower than 1%, cooling a reactant mixture to a temperature lower than 30 DEG C; or, mixing 4,6-dyhydroxy
pyrimidine with
phosphorus oxychloride, controlling the temperature to be 50-110 DEG C, adding
phosphorus pentachloride batch by batch, reacting, stopping the reaction until the content of 4,6-dyhydroxy pyrimidine is lower than 1%, cooling the reactant mixture to a temperature lower than 30 DEG C; 2) carrying out reduced pressure
distillation on the reactant mixture to recover phosphorus oxychloride; and 3) purifying the reactant mixture from which phosphorus oxychloride is recovered in step 2), thus obtaining 4,6-dichloropyrimidine. Namely, the invention provides the method for preparing 4,6-dichloropyrimidine without utilizing an organic alkali, by which, a tedious process of recovering and recycling the organic alkali is avoided; phosphorus oxychloride can be recycled, therefore the waste of resources is avoided; and furthermore, a large amount of phosphorus-containing waste solution and waste
slag is not likely to generate.