Abstract: The theory and methodology of temperature as agroundwater tracer are reviewed. The focus is placed on related research about the temperature field and seepage field coupled modeling, the numerical simulation and the parameters inversion. A series of its applications are also presented from exchange between surface water and groundwater to groundwater leakage detection (taking dam as an example). The focus and difficult point of previous research is about fractured medium, unsaturated region, complex boundary, and non-Darcy seepage. In the future research, it is necessary to improve the models and the numerical solution techniques for enabling the models to meet the complex medium, complex hydrodynamic conditions and complex thermal environment. For the application of temperature as a tracer, it is more effectively to determine groundwater velocity by mathematical statistics method. And further quantify research on how to detect the position and feature of leakage by temperature should be done.