The invention belongs to the technical field of medicines, relates to a preparation method of a high-efficient DPP (dipeptidyl peptidase)-IV inhibitor, and specifically relates to a compound taking uracil as a mother nucleus, or a pharmaceutically acceptable salt thereof, a preparation method, a composition and an application of the compound as the DPP-IV inhibitor in prevention or treatment of diseases which benefit from DPP-IV inhibition. The compound disclosed by the invention has a very good selective inhibition effect against DPP-IV and has very low cardiotoxicity, thereby being a DPP-IV inhibitor type medicament with great prospects.