The classification of regional flood-triggering precipitation and the zoning of flood hazards are essential approaches for urban flood prevention and drainage. This study focuses on the Wuchengxiyu Region within the Taihu Lake Basin，utilizing precipitation data from 1967 to 2021 collected from four national meteorological stations（Wuxi，Changzhou，Jiangyin，and Zhangjiagang），along with historical Meiyu and typhoon data series，to classify flood-triggering precipitation events. By integrating daily water level data from hydrological stations such as Wuxi and Changzhou，a hydrodynamic model was employed with a combined scenario method to simulate flood risk. A total of 1，183 days of flood-triggering precipitation were identified，exhibiting two dis‐ tinct monthly distribution patterns：the frequencies at Changzhou，Jiangyin，and Zhangjiagang were the highest in July，followed by August and June，while at Wuxi Station the frequencies decreased sequentially from June to August，with the peak occurring one month earlier than at the other three stations. Eighty-seven joint flood-trig‐gering precipitation events were identified across the four stations. Using the temporal overlap method，these events were classified into 30 Meiyu-type，16 typhoon-type，4 typhoon-Meiyu combined type，and 37 othertype events. Their temporal distributions showed approximately unimodal normal，bimodal，left-skewed unimodal，and right-skewed unimodal patterns，respectively. The cumulative flood-triggering precipitation amounts， from highest to lowest，were other-type，Meiyu-type，typhoon-type，and typhoon-Meiyu combined type. The spatial distributions of the four flood-triggering precipitation types differed significantly：except for the typhoontype，which had its high-value zone in Wuxi，the other three types exhibited low-value zones in Wuxi. Based on two key stages of urbanization in 2010 and 2020，coupled with the four flood-triggering precipitation types，two spatial distribution weighting schemes，three levels of external inflow impact，and two drainage capacity levels， 96 storm flood inundation scenarios were simulated for the Wuchengxiyu Region. The main conclusions are as follows：（1）High-risk zones（corresponding to Level 1）are concentrated along rivers and their banks，with their areal proportion，mean，and standard deviation increasing with greater precipitation weighting；（2）After accounting for major land use types，drainage measures can reduce the proportion of high-risk zones on artificial surfaces by 2. 65%-23. 78%；（3）Liangxi District of Wuxi exhibits the highest proportion of high-risk zones on artificial surfaces among all districts（cities），which may be attributed to the earlier peak month of flood-trigger‐ing precipitation in Wuxi and its topographical feature of "higher in the south and lower in the north"，followed by Tianning District of Changzhou and Zhangjiagang of Suzhou；（4）Topography and land use types are key fac‐ tors controlling inundation outcomes，while differences in high-risk zone distributions are associated with floodtriggering types，weighting schemes，and drainage measures. This study can provide a decision-making basis and context for watershed-regional-urban flood prevention and drainage，contributing to the coordinated development of the Yangtze River Economic Belt and Yangtze River Delta integration.