Abstract: With the rapid development of the social economy, the impact of high-intensity human activities on the runoff process is becoming increasingly pronounced. In order to explore the influence of human activities on runoff changes in the Luo River Basin, this study, based on the analysis of the characteristics of runoff evolution in the basin, improved traditional hydrological simulation methods using the SWAT model. By incorporating the reservoir module and considering the impact of dynamic changes in land use on hydrological simulation, the improved hydrological simulation method was applied to quantitatively analyze the impacts of micro-scale human activities, such as reservoir construction and land use changes, on runoff changes. The results show:（1） From 1961 to 2020, the annual runoff in the Luo River Basin exhibited a significant decreasing trend, with an average annual reduction of about 0.12 billion m3. The Pettitt mutation test revealed a significant change in runoff in 1989, leading to the division of the study period into a baseline period（1961-1988） and a human activity impact period（1989-2020）.（2） The SWAT model, parameterized using a regionalized approach, effectively simulated the runoff processes in the Luo River Basin. With the inclusion of the reservoir module, the model’s performance was further improved, achieving Nash-Sutcliffe efficiency coefficients（NSE） greater than 0.8 and relative errors（RE） less than 10% during both calibration and validation periods.（3） The contributions of climate change and human activities to runoff reduction were 32.9% and 67.1%, respectively, with human activities being the primary factor driving runoff changes. Among the micro-scale human factors, the construction of Gu County reservoir had the largest impact on runoff, contributing 47.9%. The contribution rate of underlying surface dynamic change to runoff reduction is-3.0%. Other human activities, such as small reservoirs, rubber dams, earth dams, and canal systems, contributed 22.2% to runoff reduction. The findings of this study provide a scientific basis for the rational development and utilization of water resources in the Luo River Basin.