Abstract: Physical and chemical analysis，SEM-EDS detection，Factsage calculation，wettability analysis of the MgO-C refractory bricks at the slag line of ladle in LF refining before and after service were analyzed，and the erosion mechanism of MgO-C refractory brick was studied. The results showed that，the different temperature of the area where the MgO-C brick locates and the different structure of the MgO-C brick led to the different wear mechanism of refractory. In the hotter area closing to the molten steel，the MgO could react with C and formed a decarburization layer. The wettability between molten slag and MgO-C refractory brick was much better，and the solubility of MgO in the molten slag was much greater. Compared with the cooler area closing to the air，the erosion of MgO-C refractory brick was much serious in the hotter area. There were some differences of the impurity composition and structure between each MgO aggregate. The MgO aggregate with more impurity and small scale of MgO grain would be eroded more easily by molten slag for the good wettability between molten slag and MgO component. The molten slag would penetrate into the MgO aggregate through the grain boundaries，causing the disaggregation of MgO aggregate and the generation of Mg2SiO4 by further reaction. Besides，the redox reaction between molten slag and MgO-C refractory brick was also the main cause of the wear of refractory.

Key words: MgO-C brick, erosion, solubility of MgO；wettability