[目的] 分析兰江流域径流对气候变化的水文过程响应，为区域水资源可持续发展和防洪抗旱提供科学基础。[方法] 利用2015—2018年日降雨径流过程和6场暴雨洪水过程率定并验证HEC-HMS水文模型在该流域的适用性；基于SDSM统计降尺度模型，对2030—2100年CanESM2模式下RCP2.6，RCP4.5和RCP8.53种情景的气候数据进行降尺度，生成兰江流域6个气象站点未来日降水序列以预测未来气候变化下的径流响应。[结果] HEC-HMS模型对场次洪水和逐日径流模拟的相关系数平均值达到0.89，0.77，平均效率系数达到0.86，0.76；RCP2.6情景下研究区面降水量较于基准期（2015—2018年）减小0.82%，在RCP4.5，RCP8.5情景下分别增大6.18%，18.17%；RCP2.6，RCP4.5，RCP8.53种情景下多年平均径流相较于基准期分别增幅为17.00%，26.22%，41.93%。[结论] HEC-HMS模型在兰江流域有较好的适用性；未来兰江流域径流呈显著上升趋势，增幅程度随辐射强迫度的增加同步增大。当辐射强迫度升高至8.5 W/m2时，流域径流量平均每10 a上升49.49 m3/s。预计21世纪末多年平均径流量达到1 101 m3/s，年径流变化起伏剧烈，汛期径流占全年比例较高，旱涝事件趋于频繁，对人民福祉威胁较大。
[Objective] Runoff responses to climate changes in Lanjiang River basin were analyzed in an effort to provide a scientific basis for improving sustainable water resources, flood control, and drought resistance.[Methods] The applicability of the HEC-HMS hydrological model in this basin was determined by calibrating the processes of daily rainfall and runoff, in addition to six processes of rainstorms and floods from 2015 to 2018. Based on the statistical downscaling model (SDSM), the climate data of three climate change scenarios (RCP 2.6, RCP 4.5, and RCP 8.5) under the CANESM2 model from 2030 to 2100 were downscaled for generating future daily precipitation time series at six meteorological stations in Lanjiang River basin in order to predict the runoff in response to future climate changes.[Results] The average correlation coefficients of the HEC-HMS model for floods and daily runoff simulations were 0.89 and 0.77, respectively. The average efficiency coefficients of the HEC-HMS model for floods and daily runoff simulations were 0.86 and 0.76, respectively. Precipitation in the study area under the RCP2.6 scenario decreased by 0.82% compared with the base period (2015-2018), and increased by 6.18% and 18.17% under the RCP4.5 and RCP8.5 scenarios, respectively. Average annual runoff under the RCP2.6, RCP4.5, and RCP8.5 scenarios increased by 17.00%, 26.22%, and 41.93%, respectively, compared with the base period.[Conclusion] The HEC-HMS model is applicable for runoff simulation in the Lanjiang River basin. In the future, runoff in the Lanjiang River basin will show a significant upward trend, and increase synchronously with the enhancement of radiation forcing. When radiative forcing increases to 8.5 W/m2, runoff will increase by 49.49 m3/s every 10 years, and predictably, the average annual runoff will reach 1 101 m3/s at the end of the 21st century. Additionally, annual runoff will fluctuate sharply, runoff in the flood season will account for a higher proportion of the year, and drought and flood events will tend to be frequent.