Abstract: Affected by global climate change, urban flood disasters occur frequently. The "July 20" extremely heavy rainstorm in Zhengzhou has sounded the alarm bell for urban flood disaster prevention. In order to fully understand the risk situation of Wuxi city encountering rainstorm similar to Zhengzhou's "July 20", a 1D-2D coupled analysis model of extreme rainstorm and flooding in Wuxi city was constructed, and the historical flood characteristics of Meiyu(plum rains), typhoon and short-duration heavy rainfall in Wuxi City were comprehensively considered. A combination of 0.35 times, 0.5 times, 0.7 times and 1.0 times of Zhengzhou's "July 20" rainstorm magnitude was proposed. Twelve flood analysis scenarios were formulated to assess the risk of urban extreme rainstorms and floods, and to put forward countermeasures. The research results can provide scientific decision-making support for extreme rainstorm emergency response, coordinated rescue and disaster relief, urban planning and other practical work.