The invention relates to a steel plate bending machine for a steel structure building. The steel plate bending machine comprises a bending table. An extruding device is arranged in the middle of the bending table, an executing device is arranged at the front end of the bending table, the extruding device comprises an extruding supporting plate mounted between the inner walls of the bending table,adjusting grooves are symmetrically formed in the side wall of the bending table, the adjusting grooves are formed in two sides of the extruding supporting plate, and an extruding plate is connected in a sliding fit manner between the adjusting grooves. The steel plate bending machine can solve the following problems in an existing steel plate bending process that follow-up mounting of a steel plate is affected as the manual steel plate bending precision is poor and a worker is likely to be hurt as the steel plate rebounds if being bended and the steel plate cannot be fixed effectively if being bended. The steel plate bending machine can achieve a function of bending the steel plate precisely and safely.