Mauritanian iron ore powder (OM) has advantages of high iron grade, low aluminum content, and low loss on ignition, which can be used as a new mineral to replace low alumina limonite that has been exhausted in Australia. However, it will have a certain negative impact on sintering because of its high SiO2 content. The mechanism of SiO₂ content affecting the sintering behavior was first studied through FactSage 7.2. Then, the liquid fluidity, penetration, and high-temperature performance of different iron ore powders were compared. Finally, the optimization of ore blending structure was studied by the micro-sintering method and the sinter pot test. The results show that the increase in SiO₂ content can reduce the assimilation temperature. The low penetration of OM can lead to an increase in the amount of liquid, and the high SiO₂ content of OM increases the viscosity of the liquid phase. What is more, the increase in SiO2 also increases the formation of silicate and fayalite phase and inhibits the formation of silico-ferrite of calcium and aluminum (SFCA). To optimize ore blending structure, OM and the low SiO₂ powder OD from Australia were used together, which improves the content of SFCA by 2.04% and decreases the contents of calcium silicate and fayalite by 0.63% and 4.99%, respectively. The results of the sinter pot test indicated that the properties of sinter have been improved.