Solar grade silicon (SoG-Si) is the key material for photovoltaic applications. In this study, the silicon grain size, concentration of HF, leaching time and leaching temperature were investigated by orthogonal methods. The results showed that the silicon grain size is the most important factor for the purification of silicon. Furthermore, the obvious removal efficiency of iron and aluminum was observed when the mannitol used as the chelated reagent in HF leaching process. Inductive coupled plasma atomic emission spectroscopy (ICP-AES) results indicated that the purity of the samples improved to a large extent with the chelated reagent.