Abstract: Corrosion behavior of low-basicity converter slag on magnesia refractory was investigated with static crucible method. Erosion area and microstructure of slag were characterized and analyzed with scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results show that the corrosion behavior of magnesia crucible by high-basicity slag is primarily structural spalling caused by the penetration of slag at the solid-liquid interface. The corrosion behavior of magnesia crucible by low-basicity converter slag is caused by erosion and dissolution through the crack of crucible, which causes the crucible particles at the interface. When w(Fe₂O₃)≥20% in slag, low melting point solid solution with high FeO forms at the interface, which intensifies the erosion. The increase of basicity and the content of MgO can relieve the corrosion of crucible by converter slag.