A systematic review was conducted of isotope hydrology, focusing on the relationship between precipitation and runoff, soil moisture movement in the unsaturated zone, and source identification and age determination of groundwater, as well as paleoflooding. It was found that isotope hydrology can describe the microscopic processes of water transformation during runoff formation and watershed flow concentration. The current research progress of isotope hydrology at Hohai University is summarized, including isotope hydrology mathematical models, experiments on partitioning of isotope runoff components in plain areas, application of isotopes in groundwater, water quantity distribution during the water diversion from the Yangtze River to Taihu Lake, and tracking of nitrogen sources in a watershed. Based on the review, present limitations of research on isotope hydrology are analyzed, and prospective future directions of research on application of isotope techniques in hydrology are described.