Slag refining,as an important option for boron removal to produce solar grade silicon(SOG-Si) from metallurgical grade silicon(MG-Si),has attracted increasing attention.In this paper,Na_2CO_3-SiO_2 systems were chosen as the sodium-based refining slag materials for boron removal from molten silicon.Furthermore,the effect of Al_2O_3 addition for boron removal was studied in detail,which showed that an appropriate amount of Al_2O_3 can help retention of the basicity of the slags,hence improving the boron removal rate. Slag refining, as an important option for boron removal to produce solar grade silicon (SOG-Si) from metallurgical grade silicon (MG-Si), has attracted increasing attention.In this paper, Na_2CO_3-SiO_2 systems were chosen as the sodium-based refining slag materials for boron removal from molten silicon. Morerther, the effect of Al 2 O 3 addition for boron removal was studied in detail, which showed that an appropriate amount of Al 2 O 3 can help retain the basicity of the slags, thereby improving the boron removal rate.