Abstract: Remote sensing monitoring of submerged areas is a direct and effective method to measure flooding and directly reflects the severity of a flood disaster.In this study,the authors monitored the submerged area and dynamic changes of Dongting Lake and Poyang Lake over the middle reaches of Yangtze River with 250 m MODIS data during a flooding event.The results were verified with TM images and showed an accuracy of 94.6%.Further,the results showed that the submerged area of the Poyang Lake in 2010 was larger than other years,while the submerged area of east Dongting Lake and southwest Dongting Lake in 2002 was larger than other years.The longest duration of fluctuation was 5-6 months for the three lakes.Generally,flooding occurred during April and November but most frequently occurred from June to August.Summer is the season with the highest frequency of flood disasters in the middle reaches of the Yangtze River Basin.