Previous results showed that the temperature of the intake area in the Middle Route of South-to-North Water Diver-sion Project increases by about 1℃ in recent 50 years.In order to analyze the impact of climate change on the future water regulation quantity in the water source area of the South-to-North Water Diversion Project,the paper investigated the impact of climate change on the intake area runoff in the Middle Route of South-to-North Water Diversion Project using the WEP-L distributed hydrological model based on the CMIP3 data of WCRP.The results are of an important significance for the study of water regulation quantity in the water source area during the operation of Middle-Route of South-to-North Water Diversion Project, provide a reliable method for the study of the impact of climate change on runoff,and lay an important foundation for the analysis of the impact of climate change on hydrologic cycle.