Abstract: From October 2 to 7, 2021, a large-scale heavy rainfall occurred in Shanxi Province. Jinzhong Area was at the center of the rainstorm. The precipitation from October 3 to 6 was 193.4 mm, which was 5.5 times of the annual average value in October and 40% of the interannual value, which was the extreme value in the same period since the establishment of the station. In order to further improve the ability of flood prevention and disaster reduction, the causes of the rainstorm were analyzed from the perspective of atmospheric circulation, then the characteristics of rainstorm and flood disaster were analyzed from the aspects of rain, water and disaster, and finally the temporal and spatial distribution law of flood in October was analyzed in combination with historical records. It was found that there are only 11 records of disasters in October in Jinzhong Area since 362 B.C.; The average precipitation in October from 1958 to 2021 was 34.9 mm, showing a fluctuating upward trend with an increase rate of 1.711 mm/10a. The main characteristics of precipitation in October were the alternation of abundant and dry season and continuous dry season. The annual relative variability of precipitation was large, up to 66%. Both October and interannual precipitation changes have a main oscillation period of 26 years, with a correlation coefficient of -0.4027, showing a reverse real correlation with a lag of 4 years. The rainstorm and flood accumulated valuable experience for water workers in command and coordination, forecasting and early warning, flood prevention and dispatching, but also exposed the shortcomings of river flood control, farmland drainage, monitoring and early warning and informatization.