An easy and effective method for purifying graphene powder by removing magnetic impurities, wherein magnetic impurities are incorporated during the process of fabricating the graphene powder, is provided. The method for purifying graphene powder, the method including: (1) ball-milling a graphite material to form graphene powder; (2) dispersing the graphene powder in a solvent to form a suspension; and (3) separating magnetic impurities during stirring the suspension, by using a magnet, Wherein the magnetic impurities were incorporated into the graphene powder during ball-milling from the balls and dispersed in the suspension.