The invention discloses a special flat ladder for overhauling a double-tier-pole cross beam nut. The special flat ladder comprises a first supporting rod, a second supporting rod, a cross bar and a hoop, the first supporting rod and the second supporting rod are arranged on the same direction, one end of the cross bar is fixedly connected with one end of the first supporting rod, and the other endof the cross bar is fixedly connected with one end of the second supporting rod; and the hoop is composed of two semicircular steel plates with horizontal extension lugs. In the special flat ladder disclosed by the invention, according to the structural features of the double-tier-pole cross beam nut of a transmission line, one end of the cross bar is supported at a cross beam, the other end of the cross bar is fixedly supported on a cement rod through the hoop, the hoop and the cement rod are welded and fixed by the two supporting rods, a device is mounted and dismounted by the opening and closing of the hoop, so that a worker can directly sit on angle iron to work after climbing on the special flat ladder, the hoop and the cement rod are not only fixed firmly, but also can be dismountedconveniently, therefore the safety of the worker on the cross beam is improved on the whole, the working time is shortened, the working intensity is reduced, and the working efficiency is also improved.