Abstract: Assessment of ecosystem health by the watershed as a unit is an important foundation for the protection and management of the ecosystem. The sub-watershed of Dongting Lake was studied as evaluation unit, and the evaluation objects were divided into terrestrial, riparian and aquatic ecosystems. The evaluation index system was constructed from the viewpoint of ecosystem's physical, chemical, and biological integrity, respectively, and the ecosystem health assessment was carried out to reveal the spatial distribution of ecological health in Dongting Lake area. The results showed that: the ecosystem health condition was general in Dongting Lake area, and the area with general health level accounted for 79.4% of the total area. The terrestrial health condition of all the sub-watershed was general and most health indices ranged from 4 to 6.The differences in health status in each riparian ecosystem were large, with the health indices ranging from 1 to 8, and the area with good health conditions accounted for 30% of the total area. The level of aquatic ecosystem health conditions was good and the health indices were higher than 4. Sub-watersheds of Datong Lake located in the central part were in poor health. Measures should be taken to strengthen the efforts of returning farmland to the shores, vegetation recovery and management in riparian zone. South Dongting Lake and Xinqiang River sub-watersheds were in good ecological health, and the biodiversity conservation and prevention and management of soil erosion should be the main concerns in the future.