Iron extraction from steel slag can achieve high-value utilization. The oxidizing roasting of steel slag and the recovery of iron from magnetic separation are systematically studied. The results indicate that the main phases in steel slag are FeO and Ca₂ SiO₅ ,with an average particle size of 21. 43μm. Thermodynamic calculations and oxidizing roasting test confirm that the weakly magnetic FeO in steel slag is oriented to become strongly magnetic Fe₃ O₄ when it is roasted in CO₂ ,and both extended roasting time and temperature increase promote the formation of Fe_{3 O4. The products obtained from oxidizing roasting are finely ground to an average particle size of 28. 09 μm. Under magnetic field strength conditions of 1 000 Gs,it is possible to obtain a magnetic separation concentrate with an iron content of 53. 12% and an iron recovery rate of 90. 53% through separation.}