The invention aims at providing a reinforcing steel bar cutting-off and forming device. A lower die holder of a cutting-off and forming die is fixed to a workbench, an upper die holder is fixed to the lower position of a top board, the top board is pushed and pulled up and down through a hydraulic oil cylinder, a long reinforcing steel bar is guided through a reinforcing steel bar guide pipe connected to the lower portion of the top board to extend into a forming body, the reinforcing steel bar is cut off through a cutting-off mechanism below the upper die holder while the hydraulic oil cylinder moves downwards for forming operation, and after the reinforcing steel bar is cut off and formed, a discharging air cylinder pushes a discharging rod forwards to push the cut-off and formed reinforcing steel bar into a receiving box. After one action is finished, an arc-shaped magnetic board driven by a transverse-pull-push air cylinder pushes and pulls the reinforcing steel bar rightwards into the forming body for the next action. The reinforcing steel bar cutting-off and forming device is simple in structure, easy to operate, capable of efficiently and rapidly cutting off, forming and discharging the reinforcing steel bar and suitable for production.