Tuyere coke probing was conducted at the Baosteel Corex Plant in order to gain a better understanding of the structure of the char bed in the melter gasifier (MG).After screening,the specimens were observed by an optical microscope to determine the mechanism of the char bed formation.X-ray diffraction (XRD) was used to clarify the degree of graphitization and infer thermal history of coke.The results show that the amount of powder coming from lump coal in the burden is much more than that from coke.Based on this,measures for improving the char bed's permeability are proposed.