Citrate of thiadiazole DPP-IV inhibitor

The invention provides citrate of a thiadiazole DPP-IV inhibitor, a preparation method for citrate, a pharmaceutical composition of citrate and use of citrate in treating diseases benefited from a DPP-IV inhibitor, particularly use of citrate in treating type 2 diabetes mellitus. Researches find that compared with other salt such as fumarate and benzoate, the citrate of the compound provided by the invention has unexpected advantages. The citrate of the compound provided by the invention is easy to salify and can be conveniently prepared with a low cost and a high yield. The citrate of the compound provided by the invention has relatively good pharmacokinetic parameters, for example, relatively high bioavailability. The citrate of the compound provided by the invention has better chemical and physical stabilities, for example, few impurities are formed in a high-temperature or high-humidity condition or in preparation and storage periods.