Abstract: In recent years, due to global climate change, China has experienced an increasing frequency of extreme weather events, with heightened threats from extreme, sudden, and destructive floods and droughts. Specifically, urban basin flood is more harmful than typical urban floods, therefore, post-disaster investigations and analyses of rainstorm and flood events are of great significance. The “23·7” Haihe Basin extraordinary flood is the largest basin flood in Beijing since 1963． To comprehensively, objectively describe the rainstorm flood process will help to elucidate the causes, development, magnitude of the flood, useful for future water conservancy planning, engineering construction, flood control and disaster reduction in the Haihe Basin. This paper conducts a thorough analysis of the climatic background, spatial and temporal distribution, rainstorm centers, and paths of the "23·7" rainstorm in the Haihe River basin. It systematically analyzes the flood process, flood return periods, inundation and erosion conditions, and comprehensively summarizes the characteristics of the "23·7" rainstorm and flood, comparing them with historical rainstorm and flood events． These data will be helpful for construction of Beijing's "three lines of defense" for hydrological monitoring, flood control and disaster reduction and for promotion of the development of river basin water conservancy．