The aluminum oxide inclusions in SWRS82B steel seriously affect the drawing performance of the steel strand. In this study, the influence of different additions of cerium (within the range of 0–0.034%) on the composition, morphology, size, number, and distribution of alumina inclusions was studied by scanning electron microscope and energy spectrum analyzer. The evolution of the composition of inclusions with different cerium additions was calculated based on classical thermodynamics and Factsage software calculation. The thermodynamic calculated results were consistent with the experimental results. It indicates that the modification route of Al₂O₃ inclusions in SWRS82B steel by increased cerium additions is as follows: Al₂O₃ → Ce₂S₃ + CeAlO₃ + Ce₂O₂S + Al₂O₃ → Ce₂S₃ + CeAlO₃ + Ce₂O₂S/Ce₂S₃ + Ce₂O₂S → Ce₂S₃ + Ce₂O₂S. Besides, when the amount of cerium is in the range of 0.023% to 0.030%, CeAlO₃ inclusions gradually disappear. The best characteristics of inclusions in this study were obtained in experimental samples with cerium addition of 0.023%, in which the minimum size of inclusions is in the range of 3.52–4.84 μm and mostly uniform distribution. Finally, the mechanism on the modification by cerium was discussed based on the composition evolution of inclusion during solidification with Factsage calculation and experimental results. The compositions of inclusions were also analyzed based on the inclusion evolution model.