Through analysis of the block model and regional model of COREX PCI process, the effect of PCI on the lump coal consumption, the gas volume of the raceway and the theoretical flame temperature are studied in this paper. The results show that when the PCI is increased, the gas volume of the raceway is enlarged; the lump coal consumption and the theoretical flame temperature are decreased; At last, a two-dimensional (2D) physical thermal model is established in this paper, then the state inside the model is simulated with the particles of wax and maize. The results show that the operating parameters affected the COREX melter gasifier clearly.