NOVELTY - A solution containing 5-methyl-pyridine-dicarboxylate and 1,2-dichloroethane is added into reactor, and reacted with aqueous solution of sodium hypochlorite and concentrated hydrochloric acid. The product is subjected to high-performance liquid chromatography. The organic phase obtained is separated, reacted with triethylamine, filtered, 1,2-dichloroethane is added, and filtered, to obtain quaternary ammonium salt. Then, quaternary ammonium salt is reacted with sodium methoxide solution, distilled, and extracted, to obtain 5-(methoxymethyl)-2,3-pyridine dicarboxylate.    USE - Preparation of 5-(methoxymethyl)-2,3-pyridine dicarboxylate used as herbicide.    ADVANTAGE - The method environmentally-friendly enables preparation of 5-(methoxymethyl)-2,3-pyridine dicarboxylate without using chemical catalyst.    DETAILED DESCRIPTION - A solution containing 5-methyl-pyridine-dicarboxylate and 1,2-dichloroethane is added into a reactor, heated at 69-75 degrees C, aqueous solution of sodium hypochlorite and concentrated hydrochloric acid is added dropwise, reactor is illuminated, pH of the reaction solution is adjusted to 3-6, stirred, and reacted for 1 hour or more. The resulted product is subjected to high-performance liquid chromatography tracking experiment, and sodium hydroxide and residual acid are obtained at the end of reaction. The organic phase obtained is separated, cooled, supplied into a reactor, heated at 25-40 degrees C and evacuated to 200 MPa. Then, triethylamine is slowly added into reactor, stirred, reacted for 1 hour or more, and filtered in filter press, to obtain quaternary ammonium salt crude product. To the resulted product 1,2-dichloroethane is added, stirred, and filtered, to obtain quaternary ammonium salt. Then, 20 wt.% quaternary ammonium salt is supplied into a reactor, sodium methoxide solution is added, heated at reflux under nitrogen protection, and cooled to 5 degrees C. The resulted product is subjected to distillation for removing acetic acid and methanol, and resulted product is extracted using dichloromethane, to obtain 5-(methoxymethyl)-2,3-pyridine dicarboxylate.