Abstract: Under the background of global climate change, the runoff of the four major river systems of Dongting Lake has changed significantly, which in turn leads to alterations in the water resources and hydrological elements of the  Lake basin. In order to explore the change trend of the runoff of the four major river systems into Dongting Lake in the future, the SWAT model of the Dongting Lake basin was established. By controlling the dual variables of temperature and precipitation, 14 different climate change scenarios were set up. calculations and analyses were conducted to assess the impact of different temperature and precipitation change scenarios on the runoff of the four major water systems into Dongting Lake. The results showed that: (1) In both annual and monthly scales, all of the simulation results of Nash efficiency coefficient and correlation coefficient for the calibration and validation periods were greater than the qualified standard, and nearly 2/3 of the simulation results met the excellent standard. The monthly simulation results of the runoff were better than those at an annual scale. The results indicated that the established SWAT model could be well applied to the simulation and prediction of the runoff. (2) It was predicted that the annual and monthly runoffs would vary significantly. The runoff increased significantly with an increased precipitation, but decreased slightly with a rising temperature. This suggested that precipitation changes had a greater impact on runoff than temperature changes. This study provided reference and data support for assessing the impact of future climate changes in hydrology and water resources of the Dongting Lake Basin and for a rational formulation of the basin development strategies.