The effects of the particle size of ground metallurgical grade silicon (MG-Si), the sort of acids, and the type of stirring on the purified efficiency of MG-Si were investigated. It was found that a particle size less than 0.1 mn was most effective for acid leaching; the extraction yield of impurities was increased by 9% with I-IF leaching compared with HCl leaching and HNO3 leaching, and increased by 7% with ultrasonic stirring compared with mechanical stilting. The principle of hydrometallurgical purification of metallurgical grade silicon under ultrasonic fields was also discussed.