The slag corrosion resistance of MgO-MgAl2O4, MgO-MgAl2O4-ZrO2, MgO-MgAl2O4-TiO2 and MgO-ZrO2 materials has been studied according to the slag corrosion extent and the change of slag chemical composition. The results were compared to those of the MgO-Cr2O3 refractory used for the RH low vessel. It can be concluded that, among the chromium-free materials tested above, the MgO-ZrO2 refractory will be better for the RH vacuum vessel.