Abstract: Since 1956, the Dongting lake basin has experienced a historical process from shrinkage to development. To investigate the reason behind its evolution during each historical stage and predict its evolution trend, we work out this study based on data of water-sediment discharge, lake-basin water surface area and lake capacity during 1956-2019, in which contribution ratios of sedimentation, lake basin subsidence, reclamation and sand mining on lake-capacity variation are identified using the variable separation method. Results show that the lake-basin water surface area decreased by 1 247.59 km2 during 1956-2019, in which the shrinkage of the east lake basin was the most severe, and reclamation within the lake basin was the major driving factor during 1956-1980, whereas the lake-basin water surface area became stable after 1980. Both sediment input and output continuously declined before the impoundment of the Three Gorges Dam（1956-2002）, with a rough sedimentation ratio of 70% in the lake. However, sediment input experienced a remarkable reduction after the impoundment（2003-2019）, with the sedimentation ratio falling to 14%. There was an offset effect among lake-basin subsidence, sand mining and sedimentation when they altered the lake capacity. At present, the lake basin is still in a slow tectonic subsidence, with an average rate of 3mm/a. As sand minning proceeds, the lake shrinkage slows down. Before 1980, the lake capacity decreased, with contribution ratios of reclamation, sedimentation and tectonic subsidence were-92.7%,-13.2% and 5.9%. However, after 1980, the lake capacity witnessed a shift from declination during 1981-2002 to augment during 2003-2019 and a net declination, with contribution ratios of sedimentation and tectonic subsidence were-107.6% and 7.6% during 1981-2002 and those of sedimentation, tectonic subsidence and sand mining were-11%, 24.8% and 86.2% during 2003-2019. Considering the higher rate of tectonic subsidence than sedimentation after the impoundment of the Three Gorges Dam and the dominance of sand mining in the lake capacity change, the Dongting lake will continuously develop as the new sand mining planning（2023-2027） implements.