Abstract: In order to provide technical supports for the planning of Water and drought prevention and control, this work studied the change of runoff and hydrological drought of the Jialing River Basin under the background of climate change. Based on the hydro-meteorological data of the Basin from 1980 to 2020, a hydrological model was developed using SWAT. Driven by four scenarios of the CMIP6 data from five meteorological models, the model was used to project future changes in runoff in the Basin under future climate change from 2021 to 2100. The results showed that (1) The SWAT model performed well in the Basin. The R2 , NES of the simulated monthly runoff at the Beibei hydrological station were both greater than 0.8, with PBIAS less than ±10; (2)The CMIP6 data after statistical downscaling based on the historical period provided reliable runoff and drought estimates; (3)A weighted multi-model ensemble could improve the simulation accuracy and reduce the uncertainty of a single CMIP6 climate model; (4) Compared with the historical period (1980-2014), the temperature, precipitation, and evapotranspiration in the Basin all showed an increasing trend, for future climate scenarios, which implied that the Basin may become more humid and hotter. The runoff showed a significant increasing trend under the SSP1-2.6 scenario, while for other scenarios, the trend was not significant. The annual average runoff was lower than the historical runoff; (5) From the perspective of SRI at the scale of 12 months, the overall trend of the Basin was becoming more humid. Hydrological droughts were reduced under the SSP1-2.6 scenario, while in the other scenarios there was a fluctuation of various drought indicators; (6) From the perspective of SRI at the scale of one month, hydrological droughts in the Basin was mainly concentrated in autumn and winter. It was shown that there existed a shift from autumn drought to winter drought, in the scenarios other than SSP5-8.5.