Abstract: Water resources is of significant importance to the national security and economic development.With the increasing of population and environmental pollution, reasonable protection and planning are the key strategy to keep the sustainable development of national water resources.Long-term water demand prediction is always the hot spot at home and abroad.In this paper, we have systematically analyzed the prediction methods about water resources, and all these methods have been divided into two groups, the whole prediction method and the section prediction method.The water demand will be regarded as a whole part in the whole prediction method, and grey prediction, regression analysis and artificial neutral network are the common methods.While the section prediction method begin with four subsections, which are agriculture, industry, resident and ecosystem.Besides, the disadvantages of these methods are analyzed and the future trends in the water demand prediction are also summarized in this paper, which can give the theoretical support for national water demand prediction.