Abstract: As the world’s largest hydraulic engineering project, the Three Gorges Project has played a vital role in flood control, power generation, navigation, and water resource utilization. Meanwhile, the ecological and environmental impacts of the associated resettlement project have attracted significant attention. This study takes Zigui County, located at the head of the Three Gorges Reservoir, as a case to quantitatively assess the changes in cropland, water, and ecological carrying capacities from 2000 to 2020, as well as the effectiveness of ecological governance. The results show that 51.3% of the area experienced improvements in cropland carrying capacity, with the proportion of grain-surplus villages rising from 50.8% in 2000 to 67.5% in 2020. However, cropland overload remains a concern in reservoir submersion zones, the dam area, and resettlement zones. The water resource carrying capacity increased from 470 thousand to 1.17 million people, significantly exceeding the actual population and maintaining an overall surplus. By 2020, 66% of villages reached ecological balance or surplus status, marking a 30 percentage point increase over 2000. From 2000 to 2020, ecosystem carbon sequestration and water conservation capacity rose by 13.4% and 35.03%, respectively, while the proportion of areas with moderate or higher soil erosion declined to 17.82%. These findings indicate that the Three Gorges Reservoir area has shifted from an early stage of limited environmental capacity to improved resource carrying capacity and effective ecological governance. Policies on out-migration resettlement and ecological conservation have played a crucial role. Special attention should be given to the ecological overload issues that persist in parts of the southern region, which should become a focus of future support and ecological protection efforts in the post-relocation stage.