<p>Heterogeneous nucleation, characterized by its low nucleation barrier and controllable nucleation sites, has been widely employed to manipulate the microstructures and properties of metallic materials. In recent years, the dispersion of inclusions, carbides, and microstructure refinement in steel have emerged as one of the key research directions in the development of high-quality steel. The current research status regarding the regulation of inclusions, carbides, and microstructures in steel through heterogeneous nucleation are reviewed. The key points and challenges in refining the second phase and microstructure in steel using inclusion particles are highlighted, aiming to provide inspiration and references for future scholars. Deoxidized inclusions, when refined and dispersed, exhibit favorable lattice matching with second phases (e.g., nitrides, sulfides, carbides) in steel. This characteristic serves as the fundamental mechanism for achieving refinement of the second phase. Concurrently, the solid-solution alloying effect from deoxidizing metals contributes to second-phase refinement, an aspect that requires prioritized investigation. In addition to the single heterogeneous nucleation refinement effect, the two-stage heterogeneous nucleation refinement of the second phase and microstructure offers a new approach for follow-up research. Notably, second-phase particles added as heterogeneous nucleation sites via external addition often require surface modification to ensure their stable retention in steel at high temperatures, which remains a major challenge restricting the widespread application of this method. Currently, the explanation of heterogeneous nucleation phenomena primarily relies on empirical calculations of lattice mismatch between the substrate and the nucleating phase, which cannot fully elucidate the quantitative relationship on the interface between the substrate and the nucleation phase. On this basis, quantifying the electronic structure and nucleation barrier at the interface between the substrate and the nucleation phase is a critical direction worthy of increased attention in the future.</p>