The invention relates to medium-deep hole blasting in underground mines, and in particular to a medium-deep hole plugging device. The medium-deep hole plugging device comprises a tamping rod, an ironwire and a plug. The diameter of the plug is smaller than the inner diameter of a medium-deep hole, and a positioning nail is arranged on one side of the top of the medium-deep hole. One end of the iron wire is connected with the plug, and the other end of the iron wire is connected with the positioning nail. The tamping rod is positioned in the medium-deep hole, and the iron wire is wound on theplug. The medium-deep hole plugging device has a simple and reasonable structure, is easy to manufacture, can solve the problems of difficulty and insecurity for construction personnel when holes areplugged, and can improve the working efficiency.