Abstract: Using the FloodArea model, the socioeconomic impacts of the extremely heavy rainfall caused by the northward movement of typhoon Dusuri during 29–31 Jul 2023, are herein evaluated. The model is validated by the disaster data of this extreme event. The results indicate a high risk of flash floods near the low-lying river channels and mountain valleys in the Hutuo River basin, China. The maximum submergence depth of the basin during this heavy rainfall is 2.9 m. A population of 512000 is affected by the involved flood, with the affected Gross Domestic Product (GDP) being 7.33 billion yuan. Moreover, 909.8 km² of farmland and 86.7 km² of residential land are affected. The simulated maximum submergence depth, affected GDP, and affected area are consistent with those of the actual survey. The results show that the FloodArea model has a good flood-submergence simulation effect for the Hutuo River basin and that it can be used for risk assessment and early warnings of rainstorms and flood disasters. Overall, the evaluation results of rainstorms and flood disasters can provide guidance for disaster prevention and relief work of governments and related departments.