The invention relates to the field of insecticide synthesis, and discloses a preparation method of chlorantraniliprole. The preparation method comprises the following steps: synthesis of an intermediate I, synthesis of an intermediate II and synthesis of chlorantraniliprole. The method comprises the following steps: reacting 2, 3, 6-trichloropyridine serving as a
raw material with hydrazine
hydrate under the action of a catalyst A to obtain 3, 6-dichloro-2-hydrazinopyridine, carrying out hydrogenation reduction reaction under the action of a catalyst B to obtain an intermediate I, reacting theintermediate I with diethyl maleate, and preparing the 2-(3-chloropyridine-2-yl)-5-hydroxypyrazole-3-
ethyl formate under the action of a catalyst C, and hydrolyzing after bromination to obtain an intermediate II, and preparing chlorantraniliprole from the intermediate II. According to the invention, 2, 3, 6-trichloropyridine is adopted to replace 2, 3-dichloropyridine as a
raw material to preparethe intermediate I, so that the defects of difficulty in obtaining the 2, 3-dichloropyridine
raw material, harsh synthesis conditions, low yield and the like are avoided, the total reaction yield ofthe intermediate I is improved, the intermediate II is prepared by a one-pot method, the post-treatment operation is reduced, and the synthesis cost of chlorantraniliprole is reduced.