Abstract: Based on the Landsat remote sensing image data of Poyang Lake from 1977-2021 and the land use data of Poyang Lake basin from 1980 to 2020, the improved normalized difference water index (MNDWI) was selected to extract the area of Poyang Lake and analyze the area change trend. At the same time, transfer matrix, standard deviation ellipse and Pearson correlation analysis methods are used to explore the characteristics and driving mechanism of water area change in flood season. The research shows that the water area of Poyang Lake in the flood season from 1977 to 2021 generally presents a downward trend, and the lake area decreases by 10.29 km²/a. The time sequence change of the water area of Poyang Lake in the flood season is generally divided into three stages: slow shrinkage period, obvious shrinkage period, and obvious growth period; According to the dynamic degree of land use, the area of urban and rural industrial land has the fastest growth, with the dynamic degree reaching 3.15%; The area of unused land, forest land and cultivated land showed a downward trend; According to the correlation analysis, the change of lake area shows a significant negative correlation with the total population at the end of the year, and a significant negative correlation with the gross national product. After the reform and opening up, human activities such as population growth, human reclamation activities and the construction of water conservancy projects have gradually become the leading factors affecting the change of water area of Poyang Lake during the flood season.