A one-step molten salt electrochemical strategy was proposed to synthesize SiC nanoparticles from ultra-fine silicon dioxide/carbon (SiO₂/C) mixtures. The electrosynthesis process and physicochemical properties of the synthesized products were systematically analyzed via X-ray diffraction, electron microscopy, Raman spectroscopy and photoluminescence spectroscopy, etc. A combined chemical/electrochemical reaction, electrochemical deoxidation, and in-situ carbonization reaction mechanism was proposed to reveal the electrochemical synthesis process of SiC nanoparticles from SiO₂/C in molten CaCl₂. The as-prepared SiC with particle size ranging from 8 to 14 nm possesses a polycrystalline structure. In addition, the SiC nanoparticles demonstrate obvious photoluminescence property due to the synergetic size effect and microstructural characteristics.