[Objective] Runoff changes under the combined influence of climate change and human activities. Exploring the temporal and spatial evolution of runoff and its causes has important guiding significance for the scientific operation of reservoirs and the sustainable use of water resources. [Methods] Based on the meteorological and hydrological data of the Wanzhou section of the Three Gorges Reservoir Area from 1960 to 2019, Mann-Kendall trend test, Pettitt mutation analysis and wavelet analysis were used to analyze the spatial and temporal evolution characteristics of runoff before and after the impoundment in the Three Gorges Reservoir Area. Finally, two Budyko hydrothermal coupling equilibrium equations were used to quantitatively calculate the influence rate of climate change and human activities on runoff change. [Results] (1) The annual runoff in the study area showed a significant downward trend (|z|＞2.58), with the inflection point appearing in 2003 (the impoundment year of the Three Gorges Reservoir Area), after which the annual distribution was more uniform. (2) Compared to the period before impoundment, the contribution rates of climate change and human activities to the reduction of annual runoff in the study area after impoundment were 27.9% to 29.2% and 70.8% to 72.1%, respectively. (3) Human activities primarily influence the annual runoff of the basin by altering the type of land use and the construction of water conservation projects. [Conclusion] This study quantitatively describes the impact of human activities on runoff changes, and provides the oretical support for the next stage of water resources management in the Three Gorges Reservoir Area.