Abstract: To achieve large transmission capacity, it is beneficial to use the high-temperature superconducting (HTS) cables to metropolitan areas with their high capacity and low losses. However, these merits only present when the HTS layers are working in certain low temperature range. In practical applications, the HTS cable might be subjected to the over-current fault. Consequently, the temperature of HTS cable will rise because of increasing resistivity of the YBCO material which will result in the reduction of transmission capacity, increase of the power loss and even burned the HTS tapes. Therefore, it is necessary to investigate the thermal behavior under the fault current. In this paper, an electro-thermal coupling model for a 110 kV single phase HTS cable is built up with COMSOL Multiphysics. The convective heat transfer of liquid nitrogen (LN2) and material properties are set up carefully. In order to ensure the stability and safety of HTS cable system, the protection action time is proposed to limit the temperature rise of the superconducting layers.