Based on the research on non-isothermal flow of molten steel in the tundish, and in response to the practical demand for monitoring multi-point temperature of molten steel in the tundish under production conditions, a distributed continuous temperature measurement system embedded in the tundish for molten steel was developed to address the problem that the existing temperature measurement system in the continuous casting workshop cannot accurately and dispersedly monitor multi-point temperature. Firstly, an innovative measurement method using a through-wall blackbody cavity was proposed. The weak signal generated by the photovoltaic cell is collected with low power consumption and resistant to high-temperature leakage interference. A customized insulation box is designed through thermal conduction analysis to resist the thermal shock of the permanent layer. Finally, a comparative test was conducted on the continuous temperature measurement performance of the system. The results indicate that the blackbody cavity structure of the temperature sensing probe can sensitively detect temperature changes and the temperature measurement node can accurately collect pA level current signals. The static power consumption of the temperature measurement node is around 60 μA, and the thermal insulation box can last for 12 h to ensure that the internal temperature does not exceed 50℃. By comparing and analyzing data with high-temperature furnaces and thermocouple temperature measurement systems, it can be concluded that the overall system′s continuous temperature measurement performance is stable and accurate. In summary, the system can monitor the multi-point temperature of molten steel in the tundish, providing practical system level support for studying the non isothermal flow of molten steel in the tundish.