The complex inclusions of Al₂O₃–SiO₂ is a common inclusion in the steel, which leads to the stress concentration in the steel products. The formation of MnS on the surface of Al₂O₃–SiO₂ could reduce the stress concentration due to the high plasticity of the MnS. In this study, the formation of MnS–Al₂SiO₅ complex inclusions is investigated at the atomic level by using first principles calculation based on the density functional theory (DFT). The adsorption energy of the atoms of Mn and S on the Al₂SiO₅ (110) surface was calculated with various initial positions and sequence. The interaction among the atoms was calculated to analyze the stable structures after the adsorption of the Mn and S on the Al₂SiO₅ (110) surface. The formation of the MnS on the surface of Al₂SiO₅ was proved by analyze the structure formed by the adsorbed atoms that shows the similar tetracyclic structure of the MnS crystal.