<p>Spring steel is widely used in high-stress components due to its excellent mechanical properties, but its fatigue performance is often compromised by high-melting-point, brittle Al₂O₃–SiO₂–CaO–(MgO) system inclusions, especially for inclusions containing spine phases. This study investigates the modification of these inclusions in 60Si2Mn spring steel using mixtures of Fe powder and Na₂CO₃ with various ratios. Results show that Na₂O significantly expands the low-melting-point region of the inclusions. After Na₂CO₃ addition, both the proportion of Na₂O‑containing inclusions and the Na₂O content within them reach maximum levels after a reaction duration of 20 to 40 minutes. Adding a mixture of Fe powder and Na₂CO₃ suppresses Na₂CO₃ volatilization, with an optimal Na₂CO₃:Fe ratio of at least 1:1. Thermodynamic analysis reveals that Na₂O enters inclusions by displacing CaO in the Al₂O₃–SiO₂–CaO–(MgO) system. Moreover, the presence of Na₂O in the inclusions affects the activities of Al₂O₃, SiO₂, and CaO, thereby promoting the corresponding reactions. Moreover, Na₂O lowers the activity of the spinel phase, suppressing its precipitation from the inclusions during the solidification process. When the Na₂O content in inclusions exceeds 10 pct, no spinel precipitation occurs during solidification at temperatures above 1200&#xa0;°C. The modified inclusions exhibit markedly improved deformability during hot-rolling simulations, thereby reducing the risk of fatigue crack initiation. This work elucidates the modification mechanism and provides both theoretical insights and practical guidance for optimizing the smelting process of spring steel to enhance its service reliability.</p>