In the context of global climate change and rapid urbanization, floods caused by extreme rainstorms in Chinese cities have been on the rise. Consequently, urban flood risks evolve into a systematic threat to urban safety. Based on literature, disaster data, and statistical yearbooks, this study summarizes the evolution characteristics of urban extreme rainstorms and disaster losses in China. Four new characteristics are revealed: intensifying extremity with historical records broken; localized and nocturnal occurrences becoming more pronounced; disasters shifting to highly vulnerable areas with a surge in urban multi-dimensional exposure; and flood risks evolving into compound hazards like fourfold convergence of typhoons, rainstorms, high tides, and floods, with escalating multi-hazard effects. This study analyzes the core challenges in urban flood prevention based on a theoretical framework of "risk source-risk exposure-mitigation force" in urban safety. By integrating the concept of resilience into the entire cycle of planning, construction, and management, we propose a scientific response path to extreme rainstorm and flood disasters in cities, aiming to provide theoretical support for constructing climate-adaptive cities.