Abstract: With the release of the 14th Five-Year Plan for the Protection of Ecological Environment, strengthening environmental risk prevention and early warning has become a key focus of current environmental protection efforts. As the capital of China, Beijing has numerous rivers within its administrative boundaries, with many key risk enterprises distributed along them. Coupled with frequent cross-river and along-river transportation of hazardous chemicals, the area is highly susceptible to abrupt water pollution accidents. To address this challenge, this paper developed models to simulate these accidents in Baihe River, one of major tributary of Miyun reservoir. Through the collection of environmental risk information and field investigations, critical parameter information such as risk sources, risk receptors, hydrology and water quality, and underwater topography was systematically obtained. Furthermore, a one-dimensional and two-dimensional Hydrodynamic-water Quality Coupled Model (HQCM) was constructed for abrupt water pollution accidents in the Baihe River based on the MIKE Model. In conjunction with the practical needs of environmental risk prevention and control in Beijing, a couple of abrupt water pollution accident scenarios were simulated and analyzed using the HQCM. The resultant findings provide technical support for the prediction and early warning of abrupt water pollution accidents, which aims to help enhance the capacity to cope with abrupt water pollution accidents and ensure the water security and ecological environmental safety in Beijing.