Abstract: Weld quality management remains a pervasive challenge in bridge steel structure construction. Taking the Liuwudian Channel Bridge—the key control project of the Xiamen Third East Passage Project—as a case study, this study designs a local reference coordinate system based on the geometric characteristics of its caisson foundation, upon which automated weld coding based on local coordinates is implemented. A weld quality management platform is developed on the basis of SaaS-based BIM data services, and a systematic weld quality management workflow is established. The results and engineering practice demonstrate that the proposed system enables comprehensive, standardized, omission-free, and collaborative weld quality management, significantly enhancing overall management efficiency.