There is a great difference between hydrology and water resources in academic development. A complete scientific system has been formed for hydrology, while there is no integrated scientific system for water resources until now. Research on the natural attribute of water resources (such as regenerating mechanism) is the stretch of hydrology in hydrologic cycle, and the knowledge in water resources involve hydrology, engineering, environmental science, management science, economy and etc.. It is necessary to know this for making research on hydrology and water resources and promoting construction of the academic subjects of hydrology and water resources.