A method for treating spheroidal graphite iron includes the step: pouring molten spheroidal graphite iron into a pouring electrical furnace (1); covering the molten spheroidal graphite iron (5) with alkali slag (6) which is melted at high temperature and rich in alkali earth metal ion, rare earth metal ion, or mixture of them; connecting the molten spheroidal graphite iron (5) with the negative pole of the direct current source by one pole (7); connecting the alkali slag (6) with the positive pole of the direct current source by another pole (4), treating the molten spheroidal graphite iron (5) with the alkali slag (6) which is used as electrolyte. The method can prevent the spheroidized fading velocity of the spheroidal graphite iron. The pouring electrical furnace can be used for treating the molten spheroidal graphite iron.