To investigate the evolution of extreme runoff at the regional scale and its climatic driving mechanisms, the Huangshui River Basin, sensitive to climate change, was selected as a case study. Daily average flow data were collected from seven stations within the basin. Mann-Kendall (M-K) trend analysis and mutation tests were used to assess the interannual variation of extreme runoff and its associations with extreme precipitation and extreme high temperatures.The results show that over the past 60 years, the extreme high flow index in the basin has decreased significantly, while the extreme low flow index has increased notably. The frequency index did not show any significant trend, but all indices demonstrated persistence. A mutation in the high flow index occurred around 2000, while mutations in the low flow and frequency indices were noted in 2010. In terms of cycles, a short cycle of approximately three years was observed for all indices. Additionally, the frequency index exhibited a long cycle of 32.5 years. The variations in runoff were significantly related to an overall increase in extreme precipitation intensity, a decrease in precipitation duration, and the intensification of extreme high temperatures in the basin. Extreme high flow was positively correlated with extreme precipitation and negatively correlated with extreme high temperatures. In contrast, extreme low flow showed a primary positive correlation with extreme high temperatures, with a less significant correlation to extreme precipitation. These findings provide important insights for the utilization of water resources and flood disaster reduction in the Huangshui River Basin.