Taking the water demand of Jinan as a study object, combining with the historical water demand data in thirteen years, the paper analyzed the factors that affect water demand and determine a number of key factors and then used Matlab platform to realize network training, and predicted the water demand of three years from 2009 to 2011. The results show that the relative forecast error is small, and the predicted results agree well with the actual situation, so the method can be used to forecast the water demand of Jinan city in future planning years. On the basis of research result, it discussed and prospected the method of water demand prediction by combining with the paper achievement and problems, witch can provide references for the future research of water demand forecast.