Abstract: Taking a 30 ton of LF as an investigated object, a gray-box model to predict the end-point temperature of molten steel in LF based on the mechanism model and the black-box model was established. The heat transfer mechanism model was firstly estab-lished according to the energy conservation law. In addition, the black-box model based on partial least squares was adopted to solve the problem that the regeneration of the ladle lining and thermal effects of the alloys are difficult to accurately calculate. Finally, the two models were combined to predict the end-point temperature of molten steel in LF. Simulation results show that the hit rate within the error range of ±5℃ by partial least squares for the regeneration of ladle lining refractory and thermal effects of the alloys reaches more than 97%, and the total hit rate within the error ranges of ±5, ±8 and ±10℃ by gray-box model reaches 88%, 96% and 99%, respectively. This means the grey-box model can accurately predict the end-point temperature of LF, which provides the guid-ance for the LF refining process in this factory.