The utility model discloses a semitrailer box steel coil tool, and relates to the technical field of semitrailer boxes, in particular to a semitrailer box steel coil tool, which comprises a bottom plate, a top plate is arranged above the bottom plate, a compartment wall is sleeved outside the bottom plate and the top plate, a lifting column is movably sleeved inside the top plate, and the lifting column is movably sleeved inside the bottom plate. A telescopic column is fixedly supported on the bottom plate, an output shaft of the telescopic column is connected with a supporting frame, a limiting rod is movably sleeved with the top plate, and the bottom end of the limiting rod is fixedly connected with a supporting spring. According to the semitrailer box steel coil tool, through the arrangement of the bottom plate and the top plate, the lifting column is movably sleeved with the top plate, the telescopic column is supported above the bottom plate, the supporting frame is fixedly connected to the outer portion of an output shaft of the telescopic column, the lifting column can be supported through the supporting frame, then the position of the lifting column can be controlled, and the lifting column can ascend or descend; and other goods can be normally transported by the vehicle bottom plate without fixing the steel coil.