Abstract: Based on the results obtained from field test through two years and some relevant materials gotten by the others, the changes of flora of aquatic plants in Denghu Lake in the past forty years are discussed.The problems about aquatic plants in Denghu Lake, such as the position of the flora in China and the World, the areal-types of species and that of genera of the aquatic plants in Donghu Lake, the distributed patterns of the mono-type and oligoro-types genera, the characteristics of the Donghu Lake and those in other ten lakes.The reasons for these changes during the years 1954-1994 are also studied.