The invention relates to the field of steel structure fabrication, in particular to an assembling jig frame for a steel structure. The assembling jig frame for the steel structure comprises a base part and support parts. The assembling jig frame is characterized in that the base part comprises base main beams and tie beams perpendicularly connected with the main beams in a bolted mode, each tie beam is divided into two sections, the two sections of each tie beam are connected by adopting a long-hole bolt, and the separation distance of the main beams can be adjusted through relative motion; each support part comprises a support bottom plate, a bottom circular tube, a support circular tube, corbels, nuts, threaded rods, a top circular tube and a bracket, the support bottom plates are connected with a base in a bolted mode, the bottom circular tubes are perpendicularly welded to the support bottom plates, the support circular tubes are inserted into the bottom circular tubes, the corbels are symmetrically welded to the two side faces of each support circular tube, the brackets are perpendicularly welded to the upper portions of the top circular tubes and inserted to the upper ends of the support circular tubes, and the brackets are in contact connection with the threaded rods which are screwed in the corbels. According to the assembling jig frame for the steel structure, the assembling precision is improved, meanwhile the geometry applicable range is greatly widened, mounting and dismounting are easy, turnover and transportation are convenient, and the assembling efficiency is improved.