Abstract: With the development of spaceborne Synthetic Aperture Radar（SAR）in recent years， the acquisition ability of SAR data with large coverage， high frequency and high spatial resolution in any region of China has been greatly improved. Spaceborne SAR with all-weather and all-day earth observation capability can accurately identify and extract flood inundation range under any weather condition， which provides an important means for rapid flood monitoring and disaster assessment in China. Based on the data of GF-3 and Sentinel-1 of the European Space Agency（ESA）， an application study on dynamic emergency monitoring of flood disasters in Poyang Lake region of Jiangxi Province in 2020 was carried out. The monitoring results show that on July 17， the water area of the monitoring area reached the peak of 4 989.78 km²， and the flooded area was concentrated in the lakeside area of Poyang Lake. In Poyang County， the affect was the most serious， the affected area of cultivated land was 351.06 km²， and the affected area of construction land and forest land was 160.98 km² and 45.14 km². In Yugan County， the affected area of cultivated land was 221.81 km²， the affected area of construction land was 111.22 km²， and the affected area of forest land was 24.18 km². The application results show that the GF-3 satellite and sentinel data have the capability of disaster emergency monitoring and can provide technical support fordisaster prevention and mitigation decision.