The invention relates to a U-shaped metal pipe bending device. The device comprises a base, supporting rods, a bending mechanism, a clamping mechanism and a pushing mechanism, two supporting rods are provided, the two supporting rods are arranged at the two ends of the base separately, and the bending mechanism, the clamping mechanism and the pushing mechanism are all arranged on the base. According to the U-shaped metal pipe bending device, the clamping mechanism is used for clamping a workpiece, the bending mechanism is used for bending the workpiece, the pushing mechanism is used for discharging the workpiece, and compared with an existing bending device, the device is simple in structure, convenient to overhaul, free of electric drive, low in cost and suitable for being used in small workshops; and the bending mechanism and the clamping mechanism are in linkage, and thus on-line clamping of the workpiece is realized; meanwhile, the linkage adopts a pure mechanical structure, the stability of the device is improved, and the service life of the device is prolonged; and compared with an existing clamping mechanism, the mechanism adopts flexible clamping, the situation that the workpiece is scratched due to rigid clamping is avoided, the workpiece is protected, and the practicability is improved.