SFC (Sillico-Ferrite of Calcium) is a kind of simplified SFCA (Sillico-Ferrite of Calcium and Aluminum) with no Al 2 O 3 . SFC and SFCA are believed to be the most desirable bonding phase in sinter. In order to better understand the fundamentals of the reduction of SFC, a series of experiments on the SFC reduction were carried out in the present work, including phase equilibria tested by XRD, morphology tested by SEM-EDS, and reduction pathway under the different CO/CO 2 mixture gas at 1 000°C. The experimental results indicated, (1) in the case of CO = 20% and 40%, most of Fe 2 O 3 in SFC was reduced to FeO. The equilibrium phases were FeO, CaO•Fe 2 O 3 , and CaO•SiO 2 . (2) In the case of CO = 60%, CaO•Fe 2 O 3 was reduced to generate FeO and 2CaO•Fe 2 O 3 . The equilibrium phases were FeO, 2CaO•Fe 2 O 3 , and CaO•SiO 2 . (3) In the case of CO = 80% and 90%, FeO was reduced to Fe, and 2CaO•Fe 2 O 3 was reduced to generate Fe and CaO. The equilibrium phases were Fe, CaO, and CaO•SiO 2 . The findings from this work may provide guidelines for the improvement of sintering production and blast furnace performances.