Abstract: The influence mechanism of MgO on sintering liquid forming and solid phase reaction and the effect of MgO flux on the strength of solid phase were investigated, and sinter pot experiments were carried out. The results show that with the content of MgO in sinter increasing, the initial forming temperature of sinter liquid phase rises, but the fluidity of liquid phase and the strength of bonding phase decrease. When different MgO fluxes are used, the strength of bonding phase in sinter appears diverse. Furthermore, at 1280~C and 1 320~C, the strength of bonding phase when sintered with serpentine is much higher than that with light-burned dolomite and dolomite is the worst. Based on the yield, quality and metallurgical properties of sinter, the desirable mass fraction of MgO is about 1.2% and for MgO flux either the composite of dolomite and serpentine or the light-burned dolomite alone is better.