4,4’-Dinitrocarbanilide(DNC) was synthesized by 4-nitroaniline and triphosgene. The by-product hydrogen chloride gas was absorbed by cold methanol. It produced HCI-methanol solution which can be used for synthesizing 2-hydroxy-4,6-dimethylpyrimidine(HDP). The HDP was synthesized in the HCl-methanol as solvent with urea and acetylacetone as raw materials. Coccidiostat nicarbazin was synthesized through the reaction of DNC and the solution of HDP in methanol. Its structure was characterized by 1H NMR. The factors that influenced the reaction such as solvent, reaction temperature and feed ratio etc were optimized. The result shows, when the 4-nitroaniline to triphoshene ratio was 6:1 in xylene as solvent, reaction temperature was 130℃ and reaction time was 15h, the yield of DNC was 94%; when the acetylacetone to urea ratio was 1.0:1.1 in the HCl-methanol as solvent, reflux reaction time was 5h, the yield of HDP was above 93%; when the DNC to HDP ratio was 1.0:1.1 in methanol as solvent, the reaction was through 5h under room temperature, the total yield of Nicarbarzin could reach to 93%. Meanwhile, the production cycle was shortened and the stability of product quality was improved through parallel reactions.