Silico-ferrites of calcium and aluminum (SFCA) are formed during the sintering process, and their changes are critical to the quality of the sinter. Aiming to further clarify the effect of BaO (0 mass%, 1 mass%, 2 mass%, 3 mass%, 5 mass%, 7 mass%, and 9 mass%) on the bonding process of SFCA. In this work, X-ray diffraction (XRD), scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS), thermogravimetry-differential scanning calorimeter (TG-DSC) were used to analysis the formation mechanisms of SFCA. The results indicated that the main bonding phase was SFCA. In addition, SFCA-I, CF, C2F, and silicate existed in the BaO-free sinter. Adding a small amount of BaO (up to 2 mass%) could increase the decomposing temperature of SFCA and increase the formation of the needle-like SFCA. With the increase of BaO adding from 2 to 9 mass%, the BaFe12O19 (FB) formed could reduce the decomposing temperature of SFCA, which deteriorated the quantity of sinter. And, BaO can promote the formation of C2F in the CF and C2F system, which decreased the eutectic melting temperature of CF and C2F.