NOVELTY - A 2-chlorine-5methylpyridine synthesizing method involves adding propionaldehyde to benzylamine, and mixing for 1-2 hours. A solvent and alkali are added, and an organic layer is separated. The solution is added to an acetylation agent, and mixed. Solidifying phosgene is dissolved, and a mixture of N,Ndimethylformamide and solvent are added. BT02 is added, heated, and mixed and reacted. pH is adjusted via a water layer to be 8 to 9. The water layer is extracted at 3 times by solvent, and anhydrous sodium sulfate is dried, filtered, and decompressed and distilled.    USE - Method for synthesizing 2-chlorine-5methylpyridine as medicine and pesticide mid-body.    ADVANTAGE - The method enables simplifying technical process, providing friendly environment and easy recovery of solvent.    DETAILED DESCRIPTION - A 2-chlorine-5methylpyridine synthesizing method involves adding propionaldehyde to benzylamine at -20-50 degrees C, and mixing for 1-2 hours. A solvent and alkali are added, and an organic layer is separated. Distilled water is separated via the organic layer, and a solution of compound BT01 is obtained. The solution is added to an acetylation agent at -20-50 degrees C, and mixed for 2-5 hours. The solvent is distilled and recycled at normal pressure, and decompressed and distilled until kettle temperature is 100-140 degrees C by utilizing a pump. The solvent is refined to obtain compound BT02 by utilizing an oil pump. Solidifying phosgene is dissolved at -20-20 degrees C, and a mixture of N,Ndimethylformamide and solvent are added. BT02 is added, heated at 20-50 degrees C, and mixed and reacting for 13 hours. The solvent is distilled at normal pressure, and a coarse product is extracted by hydrochloric acid solution. The organic layer is separated for recycling the benzyl chloride as a by-product, and pH is adjusted via a water layer to be 8 to 9. The water layer is extracted at 3 times by solvent, and anhydrous sodium sulfate is dried, filtered, and decompressed and distilled to obtain 2chlorine-5-methylpyridine.