NOVELTY - A 3-chloropyridine is prepared by (A) chlorination, (B) hydrogenation, and (C) post-treatment. The 2,6-dichloropyridine is used as raw material mixed with catalyst and heated. The chlorine is filled for chlorination, where after reaction is fully performed, the solution is cooled, reduced and rectified to obtain 2,3,6-trichloropyridine. The obtained 2,3,6-trichloropyridine, acid binding agent, metal catalyst and organic dissolvent are fed into reactor. The alkali solution is added to adjust pH value of filtering solution to 7, and layering to obtain 3-chloropyridine liquid product.    USE - Method for preparation of 3-chloropyridine (claimed) used in medical and pesticide fields.    ADVANTAGE - The method has innovative process route, short reaction step, simple operation, high yield, low production cost and good environmental-friendliness. It is suitable for industrial production.    DETAILED DESCRIPTION - 3-Chloropyridine is prepared by (A) chlorination, (B) hydrogenation, and (C) post-treatment. The 2,6-dichloropyridine is used as raw material mixed with catalyst and heated. The chlorine is filled for chlorination, where after reaction is fully performed, the solution is cooled, reduced and rectified to obtain 2,3,6-trichloropyridine. The obtained 2,3,6-trichloropyridine, acid binding agent, metal catalyst and organic dissolvent are fed into reactor. In pressure of 0-10 MPa, the solution is heated, then hydrogen is filled for hydrogenation. When pH value of reaction solution is tested to 4-8, there is no more hydrogen filled. The mol ratio of trichloropyridine to acid binding agent is 1:0.5-1. The hydrogenation solution is cooled to room temperature, added with water to dissolve hydrochloride of acid binding agent and filtered. The solution is placed statically to separate water layer. The organic dissolvent layer is extracted with water-containing acid for at least 3 times, then the extracted water-containing acid layer is combined and added with water to be diluted. The alkali solution is added to adjust pH value of filtering solution to 7, and filtering solution is layered to obtain 3-chloropyridine liquid product.