Preparation method of fluazinam

The invention provides a preparation method of fluazinam. Fluazinam is prepared through a reaction of 2-amino-3-chloro-5-trifluoromethylpyridine and 2,4-dichloro-3,5-dinitrobenzotrifluoride with an inorganic alkali as an alkali and 2-methyltetrahydrofuran as a solvent. The preparation method of fluazinam, adopting 2-methyltetrahydrofuran as the solvent has the advantages of good reaction selectivity, short reaction time, substantial improvement of the productivity of every device, large productivity, suitableness for industrial production, small use amount of the solvent, mild reaction conditions, simplicity in operation, great simplification of the industrial process, and realization of obviously less hydrolysis byproduct due to the poor compatibility with water, and allows the highest mole yield to reach 98.4% and the highest purity to reach 99.8%.