Hummers method was improved by increasing the amount of potassium permanganate, and the system was replaced by concentrated V(H2SO4):V(H3PO4)= 9:1. The surface of the GO prepared by traditional Hummers method and improved Hummers method were characterized. The improved method with easier procedure produced a greater amount of hydrophilic oxidized graphene material as compared with Hummers’ method while contained a certain amount of epoxy groups with greater layer spacing in the resulting graphite oxide, which was beneficial for later sonication.