Abstract: The high-temperature metallurgical properties of sinter were investigated to improve its quality, of which the MgO contents are different, as well as the influencing mechanism of MgO on sinter. The experimental results showed that no obvious interzonal difference is found in softening temperature with increasing mass fraction of MgO, while the interzonal differences are obvious in melting and softening-melting temperature because of the increasing high melting-point MgO-containing substances in early slag. Such a result is more obvious for low-basicity sinter. Under the experimental conditions, when the mass fraction of MgO increases from 1.3% to 3.0%, the temperature of softening-melting zone of low-basicity sinter (R = 1.36) increases from 217.2°C to 325.5°C. But, for the high-basicity sinter (R = 1.76), it increases from 310.5°C to 389.3°C. A conclusion is thus drawn that decreasing MgO content is beneficial to improving the high-temperature metallurgical properties of sinter.