A systematic analysis of the changes in key driving forces affecting saltwater intrusion in the Yangtze River Estuary before and after the operation of the Three Gorges Project was conducted, including Yangtze River’s runoff into the sea, estuarine topographic and geomorphic features, estuarine tidal characteristics, sea level rise, and the occurrence and propagation of typhoons in the estuary. Combined with four typical years of 2006,2011, 2014, and 2022 with prominent saltwater intrusion, the study focused on analyzing the impact degree and effect of relevant factors. Then, a comparative analysis was performed on the differences in saltwater intrusion impacts and related characteristics at the water intakes of three major reservoirs