Abstract: This paper mainly introduces the common problems of stress concentration at the root of welding seam after welding U-rib and face groove of steel structure bridge, which are easy to produce fatigue cracks and restrict the service life of steel bridge. The automatic welding technology of robot and high frequency pulse deep penetration arc welding power source and laser-MAG arc composite welding technology are proposed. The welding method, welding process test and welding process in the welding process of U-rib and panel were tracked and studied, and the automatic application of the welding technology was prospected and suggested. The efficient automatic welding technology of full permeability weld of U-rib and face plate is adopted to comprehensively improve the welding quality of U-rib weld, thereby improving the stress characteristics of U-rib bridge panel and effectively ensuring the operational service life of steel bridge.