To maintain ecological stability and promote sustainable socioeconomic development in the Three Gorges Reservoir Area (TGRA), the sediment connectivity index and cold/hot spot analysis were employed to elucidate the spatiotemporal evolution characteristics of sediment connectivity from 1985 to 2020. The optimal parameters-based geographical detector model was used to identify the driving factors. Findings reveal that: 1) Reservoir sediment connectivity generally showed a declining trend over these 36 years, with the sediment connectivity index decreasing by 440%. A distinct spatial pattern emerged, characterized by a widespread decrease in the east and a widespread increase in the west. 2) During 1985-2000, the spatial extent of cold and hot spots indicating changes in sediment connectivity was relatively limited. Between 2000 and 2020, however, the extent of these cold and hot spot areas significantly expanded. Hot spots were primarily concentrated in the central urban area of Chongqing Municipality, while cold spots were mainly located in Kaizhou District and Yunyang County within northeastern Chongqing. 3) The spatial distribution of sediment connectivity in the reservoir area results from the coupling of multiple factors. Soil erodibility and vegetation coverage emerged as the primary drivers influencing its spatiotemporal changes. These findings indicate that effective vegetation restoration strategies and climate change adaptation measures can help reduce soil erosion within the reservoir area, thereby maintaining regional ecosystem health and supporting sustainable development.