Abstract: Through the analysis on the relationship and variable tendency between the present population situation,main index of economic development and the amount of water consumption,the quota of water consumption,meanwhile,synthetically con sidering about the variation of influential factor such as water resources condition in future,economic and social development, science and technical progress,the efficiency of water consumption and the level of water conservation,etc,the relationship between the above mentioned synthetical influential factors and the index of water demand amountis established and the variation of growth rate of water demand in future and the variation breadth of other indices such as water consumption per capita and water consumption unit value of output are confirmed Furthermore,the amount of water resources demand in 2030 and 2050 are calculated according to the predicted indices such as population and economic development of the target year.