Abstract: +100 mesh flake graphite was used as raw material to make expandable graphite via a self-made double-spiral stirring electrochemical device. XRD and FTIR were adopted to characterize the graphene nanoplatelet. XRD and FTIR were employed to analyze the influences of different electrochemical oxidation times on the structure and oxygen-containing functional groups of graphite, and SEM was adopted to characterize the morphological changes of expandable graphite and expanded graphite. The effect of oxidation time on the expansion volume during the preparation was investigated, and its influence mechanism was analyzed. The results showed that the optimum intercalation expansion conditions of the mass ratio of graphite to concentrated sulfuric acid was 1∶1.8, the current density of 3 A/dm², the reaction temperature at approximately 0 ℃ for 3 h. Expandable graphite with a fixed carbon content of 99.95% and an expansion volume of 230 mL/g was prepared. This research method provided a new idea for the green preparation of expanded graphite with a high expansion volume, and facilitated the promotion and application of electrochemical equipment and processes for the preparation of expandable graphite in graphite enterprises in China.