Lake Poyang is one of the last two large through-flow lakes in the Yangtze River Basin and plays an important role in flood regulation, water supply, water purification and biodiversity conservation. This paper provides a systematic review of the development patterns and influencing factors of the hydrological conditions and aquatic ecological environment of Lake Poyang before and after the construction and operation of the Three Gorges Project. The main conclusions are as follows: after the construction and operation of the Three Gorges Project, under the combined influence of climate change and human activities, Lake Poyang has exhibited several hydrological characteristics, including an earlier onset and longer duration of the dry season, accelerated recession rates, a shift from sediment deposition to erosion, and a significant reduction in the duration and volume of backwater. While the overall aquatic environment has shown signs of stability and improvement, certain areas are at risk of cyanobacterial blooms. Aquatic ecosystems have been challenged by a significant decline in fish species diversity and a reduction in the density and biomass of large benthic organisms. In terms of wetland ecology, vegetation productivity has shifted towards the central zone of the lake, and the total number of overwintering migratory birds has generally increased, although some species have experienced population declines. However, existing studies have mainly relied on periodic ecological observation data for trend analysis, with relatively few quantitative assessments, particularly in quantifying the impact of the Three Gorges Project's water storage operations on the ecological environment of Lake Poyang and the mechanisms involved. Therefore, it is essential to continue long-term monitoring and research on the hydrological conditions and ecological environment of Lake Poyang. The use of multi-dimensional models will make it possible to accurately assess the impact of large-scale hydraulic engineering projects under varying hydrological conditions on the ecological environment of Lake Poyang. This research will provide a scientific basis for wetland conservation and comprehensive regulation of large through-flow lakes.