Abstract: The abnormal increase in the temperature of the cable core is an extremely early phenomenon observed during a mining cable internal-caused fire; therefore, the cable internal-caused fire warning system relies on the prompt and accurate measurement of the cable core temperature. The paper proposed a thermal circuit model to calculate the core temperature from the surface temperature of the outer sheath of the cable. The steady-state thermal circuit model is suitable for calculating the temperature when the cable is working normally and the current is stable, whereas the transient thermal circuit model is suitable for calculating the temperature when the cable is faulty. The calculation error of the model is analyzed through the internal-caused fire experiment of the mine cable, and the feasibility of the model algorithm is verified. The results show that the values obtained using the thermal circuit model are in good agreement with the experimental values, and the relative error is less than 10 %, which can be considered to be the criterion for providing early warning in case of a mining cable internal-caused fire.