A mounting/dismounting device for a disc milling cutter comprises a support, a lifting shaft, a cutter supporting disc and a hand wheel, wherein the support comprises a frame foot formed by fixedly connecting a plurality of strip-shaped parts and a connecting threaded block fixed in the center of the upper end of the frame foot and provided with a vertical threaded hole; the lower ends of the cutter supporting disc and the lifting shaft are in threaded connection with the connecting threaded block, and the upper end of the lifting shaft is hinged with the cutter supporting disc; and the hand wheel and the lifting shaft are fixedly connected below the cutter supporting disc. When in use, the mounting/dismounting device for the disc milling cutter is placed on a workbench of a milling machine and used for operation of connecting and dismounting of the disc milling cutter and the milling machine, can lower difficulty in mounting and dismounting the disc milling cutter on the milling machine, facilitates improvement on mounting/dismounting efficiency and safety of the disc milling cutter, and has the advantages of simple structure and convenience in use.