Abstract: The assessment of supply and demand of rainfall and flood regulation service is of great significance for identifying water-logging areas, allocating natural resources rationally, optimizing rainfall and flood security patterns.Current researches mostly focus on the capacity of urban rainfall and flood regulation from the single view of supply or demand, but overlook the empirical research on the measurement of the supply and demand of the whole-scale rainfall and flood regulation service.And characteristics of spatial distribution and key driving factors affecting the balance of supply and demand for rainfall and flood regulation services remain to be explored.Taking Tongcheng County, Hubei Province as a case, this research quantified the supply capacity of spatial rainfall-flood regulation services at the county level through SCS-CN Model.Additionally, we evaluated the level of social and economic demand for rainfall and flood services using flood vulnerability indexes, identifying the spatial distribution characteristics of supply and demand and the key areas of the imbalance at the county level.Combining spearman correlation coefficient analysis and redundancy analysis, we investigated the key factors affecting the supply and demand imbalance, considering the effects of population density and construction land area on the supply and demand of rainfall and flood regulation service.Finally, rainfall and flood security patterns were built at the three scales: macroscopic, intermediate perspective, microscopic.The results proved that:(1)significant spatial difference exists in rainfall and flood regulation supply and demand in the county, necessitating an overall perspective in constructing and optimizing rainfall and flood safety patterns.(2)the central built-up area is the area with the most serious imbalance between supply and demand of rainfall and flood regulation, requiring rainfall and flood safety management and restoration measures.(3)the key factor influencing rainfall and flood regulation imbalance in the county is population density, which has a negative correlation with the risk level of rainfall and flood disasters.This research provided quantitative support and basis for identifying areas of imbalance in rainfall and flood regulation supply and demand, as well as optimizing the multi-scale rainfall-flood safety patterns within the territorial spatial planning system.