In order to improve the response speed of materials in silicothermic reduction process for magnesium production, a new technology-smelting reduction process is presented. Adding an appropriate amount of Al2O3 and SiO2 can make slag completely melt in whole reduction process, thus the reaction rate can be sped up. Through software simulation, thermodynamic analysis and experimental verification, it’s found that completely molten CaO-MgO-Al2O3-SiO2 slag can be got at 1 600 ℃ with appropriate material component. The new reduction process is thermodynamically analyzed, and the results show that in equilibrium state, when the reduction temperature is 1 600 ℃, the dew-point temperature of the magnesium vapor is 870 ℃. It suggests that the new technology is feasible.