In order to improve the effective utilization of water resources, it is necessary to carry out prediction research on the response of water resources to climate change in the future. Based on the measured meteorological data, daily precipitation and temperature data after downscaling, the SWAT model was used to simulate the spatiotemporal distribution characteristics of blue and green water resources in the base period and the next three periods, and to analyze the impact of blue water change on the combined water supply of Ganhuang Reservoir under future climate. The results showed that: In the future, the average annual precipitation in Ganghuang Reservoirs will vary from -18% to -6%, and the maximum and minimum temperature will increase by 2.12℃ and 1.66℃, respectively. Compared with the base period, the blue water resources under the two RCP concentration paths will decrease by 8%~18%, while the green water resources will increase by 5%~14%. The distribution of blue and green water resources shows significant spatial differences. Under future climate scenario, the water input from Gangnan Reservoir to Huangbizhuang Reservoir will be reduced by about 45 million m3, and the water supply risks under the two climate scenarios are 0.49 and 0.29, respectively.