Abstract: Rare earth elements serve as indispensable trace additives in the steel industry. By precisely regulating the morphology, size and distribution of inclusions within steel, rare earth treatment can extend the service life of steel, reduce defect rates and enhance environmental friendliness, thus meeting the demands for high performance and sustainable development of high-strength low-alloy steels. To achieve the effective utilisation of rare earth elements and improve the comprehensive properties of steel, researchers carried out extensive research on the modification of inclusions in steel with rare earth elements. Firstly, based on thermodynamic analysis and first-principles calculations, the spontaneous driving force and atomic-scale mechanism of rare earth-modified inclusions were elucidated. The modification mechanisms and evolution patterns of inclusion morphology, size, and distribution under rare earth addition were analyzed from two aspects including single rare earth addition and composite rare earth addition. Furthermore, the differences in treatment effects at the atomic scale between heavy rare earth Y and light rare earths such as La and Ce were analyzed. Rare earth elements can transform coarse and irregular inclusions such as Al₂O₃ and MnS in steel into fine, dispersed and spherical rare earth oxysulfides such as Ce₂O₂S and LaAlO₃. This transformation significantly improves the strength, toughness and ductility of steel. It also improves the pitting potential of inclusions to make them close to the potential of the steel matrix thus enhancing the local corrosion resistance. Finally, based on the current research status of inclusion modification technology in rare earth-modified steel, the future development trend of inclusion treatment in high-strength low-alloy steels by rare earth elements is prospected. Combining the synergistic advantages of composite addition, an innovative direction for optimizing the ratio and addition sequence of rareearth elementss is proposed. This provides new ideas for the application of rare earth-treated high-strength low-alloy steels in fields such as bridge construction, shipbuilding, oil and gas transmission pipelines and construction engineering, and promotes the high performance and sustainable development of the steel industry.