Cr2O3(8.0%~30.0%)in slag on magnesia-calcia lining of an 120 t VOD unit has been studied by using scanning elec- tron microscope analyzing the energy dispersive spectrum of reaction layer of magnesia-calcia brick.Results showed that the slag basicity and TFe content in slag were the important factors for magnesia-calcia lining erosion; with increasing slag ba- sicity(CaO/SiO
2
≥3)and decreasing TFe content in slag(≤15%)
the lining erosion decreased obviously; and as MgO content was4%~12%