To scientifically control the flood disaster and effectively reduce economic losses in the flood storage area, taking the Mengwa flood storage area in Anhui Province as the research area, the satellite images of Sentinel 1, 2 and Gaofen series were selected as the data sources. The flood submerged area was extracted rapidly by using the region growing algorithm, and the detection maps of water body’s changes during flood periods were plotted. Combined with the land-use type coverage map of Mengwa flood storage area, this study analyzed the spatiotemporal change characteristics of the disaster situation of various land-use types and the total regional disaster situation during July and August 2020 with the GIS technology in the Mengwa flood storage area. The results show that the region growing algorithm combined with multi-source remote sensing data can extract the flood area quickly and accurately, and realize the timeliness and high-frequency monitoring of flood information. In the Mengwa flood storage area, the severe disaster areas were mainly concentrated in the central and northeast regions, while the southwest areas were less affected. Farmland and aquaculture ponds were the most seriously affected, while Baozhuangwei and Zhuangtai were the least affected. There is a strong correlation between the time change of disaster area and flood storage measures, but weak correlation with the local precipitation.