Abstract: Currently, calcium treatment is widely used in industry to address the problem of alumina inclusion aggregation and nozzle clogging. However, systematic research on the modification effects of different calcium-containing alloys, calcium recovery rates, and the underlying mechanisms is still lacking. With stable calcium addition （mass fraction） of 0.015%, the modification effects of five calcium-containing alloys （SiCa, SiCaBa, low-calcium aluminum, high-calcium aluminum, and CaFe） on alumina inclusions in aluminum-deoxidized steel were comparatively investigated through individual treatment and composite premelted slag treatment processes. The results reveal that among the five alloys treated individually, SiCaBa alloy exhibits the best comprehensive modification effect, achieving the highest calcium recovery rate （about 9%）, the highest inclusion spheroidization rate （about 24%）, the smallest average size （about 1.02 μm）, and the lowest total cross-sectional area （about 0.038%）. SiCa alloy treatment ranks second, whereas the low-calcium aluminum and high-calcium aluminum alloys show poor effects. CaFe alloy shows the worst modification effect, with most inclusions remaining unmodified alumina inclusions. Composite treatment of calcium-containing alloys with oxide premelted slag demonstrates significant advantages over individual alloy treatment. The composite process increases calcium recovery rates to 10%, further promotes inclusion spheroidization and flotation removal, increases the proportion of small-sized inclusions （less than 1 μm） to 67%, and reduces the inclusion number density from 381.9 mm⁻² to 269.1 mm⁻². Among the five alloys combined with premelted slag, SiCaBa alloy still exhibits the best calcium treatment effect, followed by silicon-calcium-slag and low-calcium aluminum-slag. The calcium-iron-slag treatment effect is less ideal. This study provides theoretical basis and practical reference for optimizing calcium treatment processes and improving steel cleanliness.