It is the first large-scale welding workstation specially designed for heavy-duty box girder structure in China. The maximum load and turnover weight of the ring and C-type turning mechanism is 60 tons, the diameter of the workpiece is up to 6m, the longest is 30 meters, and the two stations have a common rail of 80m, forming a complete station with two sets of gantry welding robots. The positioner is convenient to use and can be easily opened or disassembled, and the inner mouth can be easily adjusted to adapt to various sections of the box structure beam. It is suitable for efficient welding of internal and external welds, while considering the outer T-shaped steel, flange plate, horizontal channel steel (or Angle steel). And to ensure that the workpiece to the rolling tooling lifting has enough anti-collision ability.