The invention discloses a ground connection flat steel bending device. The device comprises an upright tube, a stop disc which is fixed to the front end of the upright tube, a plate bar which consists of a plug fixed to the stop disc and provided with a square cross section, and a plate sleeve which is formed by an insertion sleeve and two parallel horizontal plates horizontally fixed to one side of the insertion sleeve, wherein a jack which is provided with a square cross section and is matched with the plug is formed in the insertion sleeve; a pin hole I and a pin hole II which are matched with pin shafts are respectively formed in the plug and the insertion sleeve; a slot I which is matched with the thickness of a flat steel is formed between the two horizontal plates. When the bending device is used, the plate bar is inserted into the jack of the plate sleeve by virtue of the plug, and the pin shafts are inserted into the pin hole II and the pin hole I in sequence to realize the connection and the fixation; then the flat steel to be bent is inserted into the slot I between the two horizontal plates, the upright tube is wrenched, and the flat steel is bent by virtue of the plate sleeve. The bending device has the advantages that the use is convenient and simple, the plate bar and the plate sleeve are connected by the pin shafts, the installation and the detachment are facilitated, the carrying is convenient, and the work efficiency is improved.