Groundwater dating is one of the key links in the study of water cycles, especially in hydrogeology. However, the proposed concept of groundwater age and its dating methods are complex and difficult to distinguish, which hinders practical application and further development. This study systematically examines the concept of groundwater age and resident time that often appear in academic circles, simultaneously differentiating and analyzing the derived idealized age, tracer age, apparent age, age distribution, and model age, and comprehensively analyzes and draws a relationship diagram among the definitions. Data of the sample collection and analysis methods, advantages, and disadvantages of the natural isotopes of groundwater dating (including the radionuclide decay method and stable nuclide linear calculation method), and the methods for detecting radionuclides produced by human activities and greenhouse gas tracers are summarized and reviewed. There are two perspectives of groundwater dating methods: water sample points and water systems. The model interpretation methods of multi-tracer combination and age data from the perspective of the water body system (dynamic) are reviewed. Furthermore, we synthetically state that the groundwater dating method should be determined comprehensively according to the research objectives and range of application of tracers, with more attention paid to the study of age distribution characterizing the spatiotemporal dynamics of groundwater systems. Future studies should strengthen the integration and model research of multidisciplinary data, such as geology, hydrology, and hydrochemistry, to establish a numerical model of groundwater flow to describe age distribution and model research.