Abstract:[Objective] The variability and persistence of runoff in the Bailong River, Gansu Province were comprehensively analyzed, and the contribution rates of climate change and human activities to annual runoff variations were analyzed quantitatively, in oreder to provide a theoretical basis for water resources planning and management in the Bailong River basin. [Methods] Based on annual and monthly rainfall and runoff data from Baiyun, Zhouqu, Wudu, and Bikou Stations in the Bailong River basin from 1961 to 2021, the Mann-Kendall trend test, sliding T-test, R/S analysis, and double cumulative curve method were employed to examine the evolution characteristics of runoff and identify the driving factors behind these changes. [Results] ① The annual runoff at Bailong River stations exhibited a declining trend to varying degrees, with runoff losses increasing from upstream to downstream. The linear tendency rates of runoff decline were Bikou station 〔-3.07×108 m3/(10 a)〕 ＞ Wudu station 〔-1.49×108 m3/(10 a)〕 ＞ Zhouqu station 〔-4.20×107 m3/(10 a)〕 ＞ Baiyun station 〔-3.40×107 m3/(10 a)〕. ② The maximum monthly runoff in the upper reaches of the Bailong River occurred in September, whereas in the middle and lower reaches, it peaked in July. Wudu station exhibited the highest extreme ratio of annual maximum runoff. ③Abrupt change points in runoff primarily occurred in 1969 and 1994, with negative change rates at all stations. This indicates that before the abrupt change, runoff was higher than the annual average, whereas after the abrupt change, it was lower. ④The Hurst index (H=0.53～0.77) suggests that runoff in the middle and lower reaches of the Bailong River will continue to decline in the future. ⑤ Climate change contributed 94.85% to the reduction in watershed runoff, while human activities accounted for 5.15%. [Conclusion] The runoff in the Bailong River basin has shown a significant downward trend following abrupt changes, and this trend is expected to persist in the future.