To explore the characteristics of changes in the hydrological regime of the Tao'er River Basin under changing environment, the PCA method was used to select IHA hydrological indicators as the ERHIs indicator system. The impact of climate change and human activities on the evolution of hydrological regime in the Tao'er River Basin was quantitatively attributed using the SWAT model and the "observation-simulation" method, and the future changes in the hydrological regime were analyzed based on CMIP6 climate models. The results show: (1) The runoff in both the upper and lower reaches of the Tao'er River Basin shows a decreasing trend, with a sudden change in the runoff series occurring in 1998. (2) The evolution of the hydrological regime in the upper reaches of the basin is mainly influenced by climate change, while the evolution in the lower reaches is affected by both climate change and human activities. (3) Compared to the baseline period, under three SSP scenarios, the future annual precipitation in the basin shows a fluctuating upward trend, the warming trend of the average annual minimum temperature is significantly higher than that of the average annual maximum temperature, the future surface water availability will decrease, and the probability of flooding will increase. The study could provide references for the planning and utilization of water resources in the Tao'er River Basin to adapt to the changing environment.