The Pidgeon process is the main process of magnesium production. The higher reduction temperature of the silicothermic process results in high energy consumption in the magnesium reduction process. Improving the reducing performance of reducing agents was one of the ways to reduce the energy consumption of metallic magnesium production. The theoretical and experimental research on the reduction of MgO in calcined dolomite was studied by the mixture of aluminum and ferrosilicon as reducing agents. The effects of aluminum dosage, reduction time and temperature on the reduction rate of magnesium were discussed. The reduction process of magnesium oxide and the phase transformation of aluminum and ferrosilicon at different temperatures were studied. The results showed that when aluminum was involved in the reduction of magnesium oxide by silicothermic method, the initial reaction temperature of reduction of MgO by silicothermic method was reduced to below 700℃, and the effect of improving the reduction rate of MgO was obvious in the low-temperature stage. The reduction process of magnesium oxide by aluminum included two aspects. On the one hand, it was directly involved in the reduction of magnesium oxide to MgO?Al2O3. With the increase of temperature, MgO?Al2O3 was further reduced by aluminum. On the other hand, aluminum and ferrosilicon from the Al3FeSi2 phase, which promoted the reduction of silicon and reduced the temperature of silicon participating in the reduction of magnesium oxide. In the presence of aluminum, the reduction process of magnesium oxide by ferrosilicon was as follows: at 700~950℃, silicon participated in a reduction in the form of Al3FeSi2, and at 1200℃, the magnesium oxide was reduced in the form of Si and FeSi2. Under the experimental conditions, when aluminum participated in the reduction of magnesium by ferrosilicon, the reduction rate of magnesium oxide increased gradually with the increase of aluminum dosage. When the aluminum dosage was 12% and 1000℃, the reduction rate of magnesium oxide can reach more than 90%. Aluminum participated in the reduction of MgO to produce alumina, which reactd with CaO and SiO2 in calcined dolomite to produce CaAl2O4, CaAl2Si2O8.