Abstract: The theory and application of heat as a tracer to interpret groundwater flowing was reviewed in this paper. The application of heat tracer in the frontier groundwater science was summarized as following: (1) interpretation of the impact of surface warming and groundwater flowing to subsurface temperature; (2) calculation of hydrogeological parameters; (3) investigation on groundwater circulation in coastal aquifer. As a tracer with low expense, no pollution and easy to be observed, heat can be applied widely in the field of subsurface hydrology and engineering. However, the technique of heat as a tracer can only be applied into the interpretation of groundwater problems in homogeneous aquifers. Research on the interaction between solid and atmosphere in subsurface environment should be enhanced.

Key words: groundwater, flow line, thermal regime, heat tracer technique, aquifer, hydrogeological parameters