Abstract: Three dimensional heat transfer model is presented by finite element software ANSYS.Based on element birth and death technology,an iterative routine for slag skull melting is established to determine effect of process condition on slag skull thickness in steady state.The result shows that BF gas temperature has an obvious influence on slag skull thickness.And cooling water velocity has less effect on it.In higher gas temperature condition,the slag skull thickness is remarkably increased by decreasing the gap width.The slag skull thickness is related obviously to the measured temperature and heat load of cooling stave.The heat transfer analysis is optimized by the iterative routine for slag skull melting in this model.The slag skull thickness on BF cooling stave can be calculated by the established model in different conditions.