The invention discloses a safety belt suspension device for a 100KV extra-high voltage GIS. The suspension device comprises suspension mechanisms which are symmetrically arranged and a steel wire rope; each suspension mechanism comprises a plurality of supporting legs, a chassis and a supporting rod; the lower ends of the supporting legs are fixedly connected with cow nose screw holes in the upper portion of a GIS isolating and connecting air chamber shell, and the upper ends of the supporting legs are fixedly connected with the edges of the corresponding chassises; each supporting rod comprises a first supporting rod body and a second supporting rod body; the lower end of each first supporting rod body is fixedly connected with the center of the corresponding chassis, the upper end of each first supporting rod body is fixedly connected with the lower end of the corresponding second supporting rod body, a round hole is formed in the upper end of each second supporting rod body, and one end of the steel wire rope penetrates the round holes to be fixedly connected with the second supporting rod bodies; the problems that when a worker carries out overhauling and cleaning on a 100KV GIS body, there is not place for a safety belt for suspending, the long-suspending high-use operation is caused, and moving work loses protection are solved, the potential safety hazard of high-altitude falling of the worker in the overhauling and cleaning work is removed, and work efficiency is improved.