Water cycle in river basins has been changed profoundly under the impacts of human activities and climate change. Scientific basis behind water issues such as flooding, water scarcity, water pollution and turbidity is evolutionary mechanism of water cycle and accompanied water environment and eco-hydrology processes. Therefore,it is desired to establish a set of nature-society dualistic water cycle theory to support effective solutions of these water issues. In this study,on the basis of brief description of dualistic water cycle research history,comparative analysis of different characteristics of natural water cycle and naturesociety dualistic water cycle is performed from aspects of driving forces, structures, functions and reactions,and basic theory of nature-society dualistic water cycle has been put forward,which includes subjective mode,scientific issues,study contents and study methods etc. Opportunities and challenges confronted by the dualistic water cycle study are also discussed,e.g.,issue and solution method of united measuring and transforming of quantity-quality-efficiency of water resources,and a study summary is given at last.