Characterizing groundwater flow patterns and preferential pathways is basic premise and hot issue for prediction of groundwater flow behavior in fractured media. With the advantage of strong space-time continuity, high spatial and temporal resolution, simple measurements as well as low cost, Distributed Temperature Sensors (DTS) has been applied in heat tracer tests to study groundwater flow and heat transport in fractured media recently. DTS based heat tracer tests have gradually become an important method to identify hydraulically active fractures and to estimate their hydraulic properties, and have provided new insights in characterizing groundwater flow in fractured media. The principles of DTS, the methods of heat tracer tests based on DTS and their applications in the characterization of groundwater flow in fractured media were introduced and summarized. Various experimental methods, application modes and range of application involving DTS were reviewed. Special attention should be paid to the vertical flow in boreholes, which is a key factor for researchers to focus in the application of DTS. Integration of various DTS based heat test methods and the combination with other tracer methods can be regarded as the research interests in the future. In addition, DTS-based heat tracer test has great potential in understanding of groundwater flow and heat transport process in fractured media, making it a promising application prospect in deep geological engineering activities including high-level radioactive waste geological disposal, exploitation of hot fractured rocks.