The invention relates to the field of welding technology of chair metal frames, and specifically discloses a welding device, which includes a first driving device and an arc welding mechanical arm. The driving end of the first driving device is provided with a mounting frame, and a first The station, the second station, the third station and the fourth station, the first station, the second station, the third station and the fourth station are distributed in a rectangle on the mounting frame, the first station, The second station, the third station and the fourth station are respectively equipped with a seat I-shaped frame fixing device, a seat frame fixing device, a seat driving tube frame fixing device and a seat frame fixing device, arc welding The arc welding free end of the mechanical arm corresponds to the contact positions of the workpieces on the seat I-frame fixing device, the seat frame fixing device, the seat driving tube frame fixing device and the seat bottom frame fixing device respectively. The invention has the characteristics of accurate welding position, reliable quality, high welding efficiency and low labor intensity.