Abstract: Analyzing the heat transfer of thermometric sensor for liquid steel, a relevant finite element model is developed for the sensor. Influencing factors on thermometry such as the structure of the sensor inner and outer layers, thermal properties and boundary conditions are discussed. Numerical simulation results revealed that the max error between modeling value and experimental value is less than 6K. The thermometric lag mainly depends on the properties of protective sheath, and the thermal parameter of the sensor can be regarded as a constant. If the convective heat transfer coefficient is great enough, its rechange has smaller effect on temperature response. These results can provide a theoretical basis for sensor optimum design and its application.