Abstract: From the middle of June to September 2022, several heavy rains hit several provinces in Pakistan, resulting in catastrophic floods that inundated large areas of land, causing significant property losses and casualties. Remote sensing monitoring has the advantages of high efficiency and wide range. This paper uses the remote sensing cloud computing platform GEE(Google Earth Engine), Sentinel-1, Sentinel-2 and other remote sensing data, and SDWI, NDWI and other water indexes to monitor the national water body range in Pakistan from June to September 2022, and focuses on the analysis of the water body inundation range in the more severely affected province of Sindh from July to August. The results show that in 2022, Pakistan's the catastrophic flood inundated a vast area and lasted for a long time. The surge of water inflow in the upper reaches of the Indus River and the continuous heavy rainfall caused the Indus River to overflow the river channel and flooded a large area of plains in southern Pakistan; From June to September, the flooded area gradually moved from the coastal area to the banks of the Indus River and the lower plains of the Indus River. Pakistan still needs to improve its flood monitoring and forecasting capacity, improve the early warning system, strengthen the construction of flood control infrastructure in the upper reaches of the Indus River, optimize the drainage system in the lower reaches, so as to further enhance its ability to cope with catastrophic floods.