The digital water networks(DWN)are established based on the digital objects and process of actual water network. The DWN were divided into three types, including spatial data, technological processes and topological relations. Adopting 3S integrated technology, knowledge map technology, component technology and integrated platform, a visualization environment of DWN was constructed. The DWN was applied to the assessment and management of water functional zone in Beijing-Tianjin-Hebei metropolitan region to realize the integration application of digital water networks visualization, aiming to provide decision and technical support for efficient utilization and management of water resources in Beijing-Tianjin-Hebei metropolitan region, and in the meantime supply a new idea and method for the development of intelligent water networks.