The present invention relates to a novel process for refining Cefmetazole sodium, comprising the steps of: 1) dissolving Cefmetazole sodium material in water, and extracting after adding a water-immiscible organic solvent(s), followed by separating the organic phase containing impurities, to provide an aqueous phase containing Cefmetazole sodium; 2) treating by adding an alkoxide of alkali metal or alkaline earth metal into the above aqueous phase, followed by filtrating the precipitate, to provide an aqueous filtrate; and 3) adding ethanol or acetone in the aqueous solution and recrystallizing, followed by centrifuging and washing the resultant crystals, to provide the refined and purified Cefmetazole sodium after drying. The purity of Cefmetazole sodium material can be greatly improved by the process of the present invention.