Abstract: The upper arch of the Xihu Road (Wenhuang Street - Zanzhang Street) bridge over Huashan River adopts a fully welded double-limb steel box arch structure. The upper arch is one of the main load-bearing components of the entire bridge, featuring high requirements for weld quality, dense welds, and a small working space. To ensure the production demands of the cross-Huashan River project, the bevel form, welding method, welding position, welding material and specification parameters were determined for the main joint types of the upper arch. Welding procedure qualification tests were carried out, and the welding process was compiled based on the test results. Through in-depth analysis of the upper arch structure, a reasonable assembly and welding sequence was determined, and measures were taken to control welding deformation, ensuring welding quality. This laid a technical foundation for the welding production of the project and has reference value for the manufacturing and welding of similar arch ribs in the future.