Abstract: Flood and tidal disasters frequently impact the Qiantang River Basin, so it is urgent to build a digital twin basin using advanced technology, which would facilitate comprehensive flood management within the basin and enhance the decision-making capabilities for flood disaster prevention.Initially, we present an analysis of the overarching design concepts of the proposed platform.Subsequently, the focus shifts to an in-depth analysis of the construction methodology for the digital twin Qiantang River Basin.This analysis is structured around three dimensions of foundational information infrastructures, the digital twin platform, and the twin scene.Specifically, there is a need to optimize the monitoring network, iteratively enhance the information network about water conservancy, and bolster the overall construction of the basin-level digital twin platform.This should be done from the viewpoint of the data baseboard, model platform, and knowledge platform, with an emphasis on constructing an integrated water disaster prevention system that incorporates “four presets” processes.The digital twin and the physical Qiantang River are expected to live as twin, map mutually and link synchronously.This paper provides a comprehensive analysis of the construction concepts for a basin-level digital twin water disaster prevention platform, offering valuable insights that may inform the development of other digital twin basins.