In this study, molten-salt electrolysis of silica was investigated to identify the role played by electrolytic conditions on the deoxidization depth. Four key conditions that included particle size, electrolytic temperature, working time, and cell voltage were systematically compared using X-ray diffraction, scanning electron microscopy (SEM), field-emission SEM, transmission electron microscopy, and X-ray photoelectron spectroscopy analyses. The results suggest that prolonging the cell voltage is another key factor that determines the reduction process. Based on the given current conditions, the order of effect on the experiment is working time, cell voltage, electrolytic temperature, and particle size. The obtained specimen under optimized condition is Si and Fe–Si alloy composite with silicon porous nanosphere and Fe–Si nanoparticles in a structure that is prepared using 10 nm SiO2 nanosphere as a raw material at 800 °C for 5 h at a cell voltage of 2.6–2.8 V. The present research provides a promising guidance for practical application using the method of molten-salt electrolysis.