The utility model discloses a forming device for reinforcing cages. The device is provided with two rotating rollers which are arranged on a supporting roller-supporting frame at intervals; one end of each rotating roller is provided with a transmission mechanism which is connected with a driving device; one side of each rotating roller is parallelly provided with rails, and a traveling trolley is arranged on the rails; and the traveling trolley is provided with a bar straightening mechanism and a guide wheel. The device is favorable for forming even pitches by hooping, has close fixation, few joints, high winding efficiency and high quality of the reinforcing cages, meets the factory production requirement, and is necessary equipment for processing the reinforcing cages.