Steel making is an energy intensive industry. Compared to other industries, steel industry has relatively large opportunity to reuse waste heat energy with high temperatures. It is well known that thermoelectric generator technology has a strong point to harvest waste thermal energy despite low power efficiency. This work describes the development of a simulator to calculate the generated power through a specified thermoelectric generator system, which is designed to covert the radiative heat energy to the available electric power. The developed simulator is based on 1D thermal system of TEG-system. User can specify the TEG system and calculate conjugate heat transfer and power generation. Validation shows that the simulator has sufficient predictability on calculating power generated according to thermal changes, temperatures of slab and coolant water. Since TEG system is installed in slab yard and environmental thermal flow changes naturally, deviations are inevitably observed.