▎ 摘　　要

NOVELTY - Preparing graphene oxide by using large-grain crystalline flake graphite involves adding hydrogen peroxide, where the grain diameter is 45-325 micrometer of large grain diameter crystalline flake graphite and concentrated sulfuric acid according to 1 g:(20-30) mL proportion, stirring uniformly, standing to obtsin mixture containing expanded graphite, adding mixed acid solution comprises concentrated sulphuric acid and phosphoric acid with volume ratio of (99-135):(11-15) into the mixture, stirring in ice water bath, and adding potassium permanganate solid powder, then raising the temperature to 40-60degrees Celsius, continuously stirring and reacting for 60-300 minutes, adding water and stirring, adding hydrogen peroxide to obtain bright yellow solution, centrifuging and washing the solution, washing to neutral, drying to obtain product. USE - Method for preparing graphene oxide by using large-grain crystalline flake graphite used to material science, physics, aerospace, energy, electronic and biological fields. ADVANTAGE - The method enables to prepare graphene oxide by large-grain crystalline flake graphite, which is simple and cost-effective, and generates large size of graphene oxide, and has high oxidation yield.