Abstract: On the basis of identifying water problems at home and abroad,this paper analyses the evolution pattern of the natural-artificial dualistic water cycle,clarifies the interactions among hydrological processes,and associated hydrochemistry,water ecology and flow-sediment processes,as well as preliminarily describes the subject system constitution of modern hydrology and water resources.Based on describing the development trend of international hydrology and water resources and hot issues and frontier problems,and combining with research status of hydrology and water resources and practical demands on solving water problems in China,we discuss the subject system of hydrology and water resources in China,and analyze the important research directions.Under the influences of environmental change and strong human activities,water cycle shows obviously the natural-artificial characters on all aspects of dynamics,structure and parameters.Modern hydrology and water resources research is changing from traditional methodology of decomposition and refinement to present emphasis on integration and crossover,and from single-hydrological-variable oriented research to integrated hydrological processes oriented research.Prototype observation and numerical simulation become a critical study method in these fields.Hydrology and water resources research needs further strengthening on the basic research of mechanism identification and quantitative simulation of the water cycle and associated processes,improving on the application basic research of assessment,allocation and regulation of water resources,water right distribution,and water pricing theory and technology,to serve water-saving society establishment,water environmental protection and ecological construction,integrated water resources management,disaster prevention and mitigation and emergency treatment,drinking water safety,hydraulic engineering construction,and other practical needs.