Jiaxing City is located in Hangjiahu Plain,the comprehensive application research of digital twin water network is developed in order to strengthen fl ood disaster risk prevention and control,strengthen water resources supervision,and optimize water resources utilization,in view of the problems such as the complex and changeable water regime,frequent fl oods,and prominent contradiction between supply and demand of water resources in the region. The rainwater situation monitoring,water conservancy project management,fl ood prevention situation judgment,joint scheduling and other modules are integrated by model analysis,functional calls,service calls,data fusion sharing and other methods,which achieves the forecast,early warning,preview and plan function of the whole region water disaster and water environment. The operation results of the system eff ectively improve the water disaster monitoring and situation analysis ability,strengthen the coordinated control of fl ood risks,and enhance the coordinated dispatch capabilities of city,county,and district water conservancy projects,which realizes the transformation from experience defense to smart defense,maximizes the effi ciency of drainage dispatching benefi ts of water conservancy projects,and improves the overall fl ood prevention and drainage and water environment improvement capabilities of the region. This research has the typicality and representativeness of the digital reform of plain river network,which can provide copy and reference experience in the digital reform of national water conservancy.