Chaobai River basin is one of the crucial water supply sources for Beijing, and it is significant to study on the variation trend of waterresources in the basin to maintain the stable ecology system and economic development. This paper simulated the hydrology cycle process in thebasin combined with the SWAT model, and analyzed the variation of blue and green water resources in the basin during 1960-2008 ， and thenmade prediction for the future. The results indicate that the blue and green water flow were decreased significantly while the green water storagewere increased slightly during the research period. The tendency rates of these hydrologic variables are -19.33mm·10a-1， -6.92 mm·10a-1 and0.70 mm·10a-1 respectively. The prediction results propose that the change trend of blue and green water resources would be continued.