Abstract: In view of the problem that low-carbon Al₂O₃-SiC-C refractories are difficult to meet requirements of modern ironmaking due to the weakening of interface bonding.Tabular corundum, 6H-SiC, α-Al₂O₃, Al powder and flake graphite were used as the main raw materials, andMgSiN₂ was introduced as an additive to prepare the refractories. The effects of MgSiN₂ additionat mass fractions of 0, 1%, 3% and 5% on the phase composition, microstructure and mechanical properties at room temperature were studied. And the mechanism was revealed by combining thermodynamics and first-principles calculations. The results show that with the increase in MgSiN₂ addition, the in-situ generated MgAl₂O₄ phase increases, and its distribution is uniform and dense. At 1 600 ℃, MgSiN₂ decomposes into generate gaseous Mg. Generate gaseous Mg promotes the in-situ formation of MgAl₂O₄ phase and its strong bonding with Al₂O₃ matrix through gas phase mass transfer, thus optimizing the microstructure of the material. Consequently, when the addition amount of MgSiN₂ is 5%(mass fraction), the mechanical properties of the material at room temperature are optimal, and the cold modulus of rupture and compressive strength are increased to 7.27 and 56.80 MPa, respectively.