Abstract: From June to August 2022, the Pearl River Basin suffered from continuous heavy rainfall and a total of eight numbered floods, presenting a severe and complicated flood control situation. During the critical period of flood control in the Pearl River basin, the Remote Sensing Technology Application Center of the Ministry of Water Resources carried out emergency remote sensing monitoring and assessment of key flood disaster areas based on the radar satellite images of China's GF-3, Hisea-1 and ESA Sentinel-1, and combined with the optical satellite images of China's GF-1 and Jilin-1. This paper carried out remote sensing dynamic monitoring and analysis on the change of water body area in Pajiang flood detention area, the opening of the polder, and the change of water body area in key flood disaster areas. The monitoring results show that on June 23, a total of 5 polder were used in the Pajiang flood detention area in the Beijiang River basin, and the water body area reached the maximum as 39.51 km². The water body area of counties and surrounding townships of Yingde City also reached the maximum on the June 23, with a remote sensing monitoring area of 143.16 km². The water body area of the Wuzhou section of the Xijiang River reached its maximum on June 19, and the area of the Siliang River, a tributary of the Guijiang River, was severely inundated.