The invention relates to an assembling platform for a driving device used for a crane. The assembling platform comprises supporting legs, an annular disc and a rotating disc. A supporting plate is fixed to the upper side faces of the supporting legs. A bearing seat is fixed to the middle of the upper side face of the supporting plate. The bearing seat comprises a bearing seat left part and a bearing seat right part. A constant-speed motor is fixed to the lower side face of the supporting plate. The constant-speed motor is connected with a gear A. An electric control box body is arranged on one side of one supporting leg. The annular disc comprises an inner ring part and an outer ring part. Threaded holes are distributed in the upper side face of the inner ring part. The threaded holes are connected with universal balls. Threaded through holes are distributed in the outer ring part and are connected with screws. A base is fixed to the middle of the upper side face of the rotating disc. A spline groove is formed in the middle of the upper side face of the base. A rotating shaft is fixed to the middle of the lower side face of the rotating disc. A gear B is arranged on the lower portion of the rotating shaft. The lower end of the rotating shaft penetrates in the bearing seat left part. The assembling platform has the beneficial effects of being capable of rotating automatically, easy to operate and high in practicability.