SummaryFloods occur more frequently in the context of climate change; however, flood monitoring capacity has not been well established. Here, we used a synergic mapping framework to characterize summer floods in the middle and lower reaches of the Yangtze River Plain and the effects on croplands in 2020, from both flood extent and intensity perspectives. We found that the total flood extent was 4936 km2from July to August, and for flood intensity, 1658, 1382, and 1896 km2of areas experienced triple, double, and single floods. A total of 2282 km2croplands (46% of the flooded area) were inundated mainly from Poyang and Dongting Lake Basins, containing a high ratio of moderate damage croplands (47%). The newly increased flooding extent in 2020 was 29% larger than the maximum ever-flooded extent in 2015–2019. This study is expected to provide a reference for rapid regional flood disaster assessment and serving mitigation.