Abstract: Driven by the dual momentum of new urbanization and Digital China, municipal water engineering—the core vehicle for water resource management in urbanization—is transitioning from conventional design toward intelligent, efficient paradigms. Yet prolonged design cycles and low efficiency continue to constrain high-quality enterprise development, representing a critical bottleneck the industry must overcome. To address this, this paper proposes a BIM collaborative design model grounded in municipal water engineering workflows. The model integrates five core functions of the collaborative design platform—parametric design, design review, quantity takeoff, intelligent drawing review, and BIM-based drawing production—to support multi-disciplinary collaboration and information sharing. Building on the BIM model, the study further explores multi-software data interoperability mechanisms, breaking down the data silos across traditional design stages. This advances the transformation of municipal water engineering from fragmented management to digital integration, and establishes a cross-disciplinary, end-to-end digital delivery standard framework.