The invention provides a bending device of a fireproof door plank. The bending device comprises a base, two supports and a bending assembly. The supports are arranged on the base. The bending assembly comprises shafts fixedly erected on the two supports, a forming block fixedly arranged on the shafts in a sleeving manner, a clamping groove in the upper surface of the forming block, two handles movably arranged on the shafts in a sleeving manner and located between the forming block and the supports, and a stop block used for pressing and bending the door plank and arranged between the two handles. The two ends of the stop block are fixedly connected with the two handles through springs. The connecting ends of the springs and the stop block are flush with the lowest point of the forming block. The handles are provided with sliding grooves. The forming block is a cylinder and is provided with a protrusion. Through cooperation of all the parts, the fireproof door plank can be bent, and requirements for modeling of the fireproof door plank in some aspects are met; the models of the two sides of the forming block are different, the requirements of different models can be met, and adaptability is high; and by means of the handles, operation is more convenient.