The invention discloses a GIS metal tank disassembling and assembling tool. The tool includes two gantry lifting frames arranged side by side, wherein each gantry lifting frame includes a cross beam;columns are vertically arranged at both ends of each cross beam; the bottom of each column is fixedly connected with a base; two hand-pulled hoists are installed at the bottom of each cross beam; andthe two hand-pulled hoists are arranged between the two columns. According to the GIS metal tank disassembling and assembling tool, the problems of limited operation space, the potential safety hazards caused by mistakenly touching nearby electrical equipment and the uncontrollable accuracy of equipment installation are overcome, so that the precise regulation and control of the GIS tank disassembly and assembly process are achieved, and thus the completing of the safe, efficient and high-quality maintenance of GIS equipment is facilitated.