Abstract:The water demands of Beijing under different scenarios (including business as usual scenario (S1), economic development scenario (S2), South-to-North Water Diversion Project scenario (S3) and comprehensive development scenario (S4)) from 2012 to 2030 were forecasted based on the system dynamics method and then the water deficit problem was analyzed. The results showed: (1) for the four scenarios, domestic water demands are on the rise, industrial water demands are on the rise under scenario S1 and S3 and are on the decline under scenario S2 and S4, agricultural water demands and environmental water demands keep stable, while the total water demands show a downward trend; (2) for the four scenarios, the average total water demand were 4.187, 4.385, 4.203, and 4.396 billion m3, respectively, the annual average water deficits for the water shortage years were 0.682, 0.759, 0.361, and 0.444 billion m3, respectively, while the average water deficit indexes were 0.1592, 0.1679, 0.0833 and 0.1592, respectively; (3) In order to ensure the rapid development of social economy and maintain water supply and demand balance and sustainable development, Beijing also needs more efforts to enhance the people’s awareness to protect water resources and save water. Only this can the long-term balance of water supply and demand be achieved in Beijing.