Influence of Ce and Al on nodularization of eutectic in austenite-bainite steel was investigated by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). Results show that CeAlO3 is formed preferentially during solidification to act as heterogeneous nuclei for the crystallization of the eutectic. The cerium and aluminum adsorb and enrich on the growing surface of the eutectic during crystallization, which makes the crystallization model of the eutectic turn from facet-nonfacet to nonfacet-nonfacet. The nodularization of the eutectic can be explained by the heterogeneous nuclei of CeAlO3 and by the influence of the modifying elements of Ce and Al on the crystallization of the eutectic.