Abstract: In this paper, expanded graphite was prepared by chemical oxidation system with hydrogen peroxide as oxidant and concentrated sulfuric acid as intercalation agent. Expanded graphite was obtained by microwave expansion. The effects of the amount of hydrogen peroxide and concentrated sulfuric acid on the morphology and specific surface area of expanded graphite were systematically studied. It was found that the expanded graphite retained the structural characteristics of natural small flake graphite and had wormlike surface morphology, The maximum expansion volume was 291.39 ml/g and the specific surface area was 55.62 m²/g. Small flake expanded graphite was used as anode material of lithium ion battery to assemble button battery and its electrochemical performance was tested which showed good lithium removal/intercalation capacity and good cycling performance.