Abstract： As a pillar industry of a country, the iron and steel industry plays an important role in the national economy. Due to the change of raw material composition, the Al2O3 content in blast furnace slag is increasing, which increases slag viscosity and brings difficulties to blast furnace smelting. Previous studies found that adding MgO flux to sinter can effectively solve this problem. At the same time, MgO also has many impacts on the metallurgical properties of the sinter. The results show that with the mass fraction of MgO decreasing from 2.8 mass% to 2.0 mass%, the cold drum strength (TI) and reduction index (RI) of sinter increase by 3.4% (from 72.1% to 75.5%) and 3.1% (from 70.3% to 73.4%)， respectively. Besides, the temperature of soft melt zone changes from 251℃ to 233℃, leading to the enlargement of the air permeability of the blast furnace, which is helpful to strengthen the smelting of the blast furnace and improve the economic benefits of the enterprise.