Abstract: The Daqing River spans four provinces(municipalities) including Shanxi, Hebei, Beijing and Tianjin, is a key location for the implementation of major national strategies such as the coordinated development of Beijing, Tianjin and Hebei and the long-term development plan of Xiong'an New Area. Its flood control safety has reached a political level. To implement the national requirements for smart water conservancy construction during the 14 th Five-Year Plan period and to improve and to enhance the flood control safety system and capabilities of the Daqing River basin, this study systematically analyzed the actual data requirements for diverse data in the construction of the “Four Preventions”(forecast, warning, rehearsal, plan) flood control data baseboard for the Daqing River; it clarified the full-process business requirements for data aggregation, governance, storage,services, transmission, and sharing; proposed a data management system characterized by a unified foundation, multi-source aggregation, standardized governance, and efficient parallel processing to support diverse data transmission and processing needs under different information formats and business application scenarios; established a multi-source, multi-scale basin-level data baseboard comprising five major categories of data(basic data, monitoring data, business data, spatial data, and cross-industry shared data) to provide systematic support for the “Four Preventions” functions of flood control in the Daqing River basin. The relevant technical achievements were applied in the simulation and analysis of the “23·7” major flood in the Daqing River system, providing references and insights for the construction of digital systems in other river basins in China.