During Ti-stabilized stainless steelmaking process, oxide inclusions in steel generally cause the clogging of submerged entry nozzle and surface defects of cold-rolled products. Therefore, the evolution mechanism of oxide inclusions in Ti-stabilized 18Cr stainless steel was investigated by industrial experiments. The characteristics of inclusions in specimens were analyzed by scanning electron microscopy and energy dispersive spectroscopy. After Al deoxidation, the main inclusions were irregular MgO–Al₂O₃ spinel. After calcium treatment, MgO–Al₂O₃ inclusions were modified to be spherical multilayer CaO–MgO–Al₂O₃ inclusions consisting of spinel crystal embedded in CaO–Al₂O₃ liquid matrix. Thermodynamic calculation indicated that several ppm Ca could significantly expand the liquid oxides phase in Mg–Al–O phase diagram. After Ti addition, multilayer CaO–MgO–Al₂O₃–TiO_x inclusions were formed. The compositions of steel were located close to Al₂O₃–TiO_x liquid oxide phase, which would help to reduce oxide inclusions and increase titanium yield. Titanium addition has modified spinel inclusions to multilayer MgO–Al₂O₃–Ti₃O₅ inclusions containing solid spinel inner layer and MgO–Al₂O₃–Ti₃O₅ liquid oxide outer layer. As for improving the cleanliness of molten steel, the contents of magnesium, aluminum, and titanium could be considered simultaneously to liquefy oxide inclusions during Ti-stabilized stainless steelmaking process.