The utility model relates to a large-tonnage ground auger structure which is composed of a drill rod part and a special fixture, the special fixture is arranged on the drill rod part in a limiting andsleeving mode, and the specific structure of the drill rod part is that rotating ribs are symmetrically and fixedly arranged on the two radial sides of the upper middle portion of a drill rod of a large-tonnage ground auger. The special fixture comprises a clamping plate, a limiting edge, a U-shaped ring and a nut, the two clamping plates are symmetrically arranged at an interval; the drill rod is installed between the two clamping plates in a penetrating mode, two limiting edges are fixedly installed in the middles of the opposite inner sides of the clamping plates at intervals, the distancebetween the two limiting edges is matched with the width of the rotating rib, two through holes are formed in the two sides of the clamping plates on the outer sides of the limiting edges respectively, and the same U-shaped ring is installed in the two through holes in the opposite sides of the two clamping plates in a penetrating mode. The utility model has the advantages of lightness, convenience in operation, detachability, safety in use and the like, ensures the safety of constructors, is convenient and quick, increases the stress, protects the ecological environment, reduces the pollution, and can be widely used in plain areas.