The utility model relates to a single-walled steel hanging box, which belongs to a deep water platform and pier column constructive and protective structure. The single-walled steel hanging box mainly comprises a lateral board and a bottom board, wherein the lateral board is formed by an upper segment and a lower segment, and the bottom board comprises a panel, a longitudinal beam and a cross beam, wherein the panel is paved on the longitudinal beam, whose one side which is parallel to the longitudinal beam is welded with an equal angle steel, and the other two sides are welded with angle-bar flanges, the lower sides of the through holes of the angle-bar flanges are welded with nuts, and the panel is also opened with a hole for helping a support guard tube to be inserted, the longitudinal beam is arranged on the cross beam, two cross beams are arranged on both sides of the hole, and both ends of the cross beams are welded anchor plates, and the anchor plates are respectively opened with a through hole relative to the inner side and the outer side of the lateral board. The bottom board of the single-walled steel hanging box can be detached, which overcomes the shortcomings of the bottom board of an original steel hanging box which can not be recovered.