The invention provides a preparation and purifying method of tiagabine hydrochloride. The method comprises the following steps: directly using R-piperidine-ethyl formateXL-tartrate(2), or R-piperidine-3-ethyl formate as raw material, reacting with alkylating agent 1,1-bi(3-methyl-2-thienyl)-4-X-1-butene(1, X is Cl, Br, I, O, Ts and OMs) in the presence of enough potassium carbonate, obtaining a crude product of tiagabine ethyl ester, directly performing alkali hydrolysis, performing the process of alkali solution in dichloromethane-water system and slat formation with hydrochloric acid on the tiagabine hydrochloride crude product for more than twice, removing various impurities in the tiagabine ethyl ester crude product to obtain pure tiagabine hydrochloride (4) with high purity. The process step is shortened, the column chromatography is abolished, the process program is simplified, the cost is greatly lowered, and the product with high purity is obtained.