Assembled U-shaped Steel Beam Assembly Machine (Equipment Traveling) is mainly used for U-shaped and box-shaped assembly in the assembly of box girders (columns). The workpiece is placed on the workpiece platform composed of multiple roller tables. Relying on the upper pressure cylinder and side pressure cylinder of the traveling gantry, the web and flange of the workpiece are pressed tightly. Spot welding is performed on the pressed part, and spot welding is performed on the entire length of the workpiece through gantry traveling. After spot welding, the workpiece is transported through the conveying roller table to enter the next backing welding process or electroslag welding process.