Abstract: Enhancing the capacity for monitoring, forecasting, and early warning of rainfall and flood conditions in high-risk flood areas represents a critical national demand and an international frontier topic, addressing the increasing frequency, scope, and disaster impacts of extreme, anomalous, and sudden flood-inducing rainstorms. Aiming to extend flood prediction lead times and improve forecast accuracy, this paper focuses on key technological challenges, including the precision of extreme precipitation monitoring and forecasting, simulation of exceedance-level floods, and the “four-Pre” (Pre-forecast, Pre-warning, Pre-simulation, Pre-planning) platform for flood control. It begins by elaborating on the key scientific problems to be addressed in rainfall and flood monitoring, forecasting, and early warning. Subsequently, a comprehensive research framework centered on “mechanism exploration–technology development–equipment innovation” is proposed. The study outlines critical technologies and research components requiring breakthroughs, such as areal rainfall monitoring and forecasting, simulation and forecasting of flood and it’s impacts, domestically produced miniaturized rainfall radars, and a universal “four-Pre” platform for flood control, along with anticipated outcomes. This research is expected to advance the construction of China’s “three lines of defense” in rainfall and flood monitoring and forecasting, providing technical support for the prevention of rainstorm and flood disasters in the country.