Abstract: Purification of metallurgical grade silicon (MG-Si) for solar grade silicon (SOG-Si) preparation with electrorefining in molten NaF-KF eutectic was studied. SEM and ICP-MS were used to examine and characterize the refining products. The effects of voltage, temperature and time on refining efficiency were analyzed and discussed. The results show that, under the refining conditions in 1073 K NaF-KF molten salt at 2.0 V for 400 min, the electrolyzed products are Si wires with length of several tens of micrometers and diameter of 50 nm to 150 nm. The removal efficiency of metal impurities from MG-Si can reach above 92%, with B and P removal efficiencies of 92.1% and 97.6% respectively. The purity of refined silicon product can reach up to 99.999%.