Abstract: Predictive water demand for high, meddle, and low levler during the planning perid 2000-2030 in Taiyuan city are presented. On this basis of the observed hydrological records the sequential generation of preciptation, runoff and groundwater recharge are conducted. By using the developed integral simulation model of water supply system the water supply risk during the planning period is analyzed quantitatively year by year. The operational probability and the expect water price of diverting water from Wuanjiazhe reservoir on Yellow river are estimated.