Based on the summary of the conception and connotation evolution of water resources bounded by other hydrologists, the paper divides water resources into generalized water resources, specialized water resources, useable water resources quantity for national economy and ecological water requirements on different caliber. It clears the argument on water resources assessment and definition in history from the double carrying object of water resources. And that it scores the object of water resources research and its contents on three layers proceeded with water resources development course, which includes basic research, applied research and integrated research. According to the contents of subject, the paper constructs the water resources research system consisted of base subject, application subject and integration subject and analysis three parts separately indepth. It is of positive significance for construction of water resources study.