Abstract: Rare and precious metal catalysts have remarkable effects on methane decomposition, but the cost is high, so that it is an important task to explore low-cost catalysts to realize their industrialization and popularization. Iron-based catalysts have the advantages of high-temperature resistance, low price and good performance. At present, there is little research on the surface mechanism of iron-based catalysts, and there is still no unified view of catalyst interface composition and structural stability. In this study, based on density functional theory (DFT), the stability of the Fe (111) /Al₂O₃ (0001) interface was studied by first principles, and the formation mechanism of the catalyst with different end faces was discussed. The results of surface energy, state density and differential charge density analysis showed that the adsorption energy and charge concentration at the O-terminal interface were greater than those at the interface of Al1 and Al2, and the charge accumulation around the O atom was obvious. Weak metal bonds were formed between Fe and Al at the interface of Al1 and Al2, while covalent, metallic and ionic bonds were formed between Fe and Al at the interface of the O terminal. The O terminal covalent bond strength was also higher than the Al1 and Al2 terminal interfaces. Therefore, the O-end Fe/Al₂O₃ catalyst was more tightly bound than other end faces, and would also show a better catalytic effect. The above research results provide a theoretical basis for preparing the interface formation mechanism of Fe/Al₂O₃ catalyst.