The invention discloses a ring main unit plug dismounting tool. The dismounting tool comprises a body, a cover plate and a snap ring, and is characterized in that the snap ring is mounted in the middle of the body; the cover plate is movably connected with the upper portion of the body through a connecting member; the cover plate is provided with a threaded hole; a bolt extends into the body through the threaded hole in the cover plate; and a cable inlet is formed in the body. By adopting the dismounting tool, during maintenance, especially in a cable plug dismounting process, the working timeis greatly shortened, the dismounting time is shortened from original 20 minutes to 10 minutes, the working efficiency of replacement equipment is improved, the labor intensity is relieved, the dismounting and mounting time is shortened, lot of unnecessary cost waste conditions are avoided, and the dismounting tool can better serve the daily production and maintenance work.