Abstract: Due to its advantages such as stable chemical property, long half-life and no extra sources during groundwater migration, ⁸¹Kr has recently become an effective method to determine the age of paleogroundwater (10⁵-10⁶ a). The overseas researches on determination of ⁸¹Kr and groundwater dating are relatively mature, yet related domestic studies are still at the beginning stage. This paper summarizes the principles of ⁸¹Kr in groundwater dating and extraction method, discusses the problems in current research, and makes prospects for the studies of radioactive Kr nuclide in hydrogeochemistry, which provides scientific basis for the researches at home.