Graphite nanosheets prepared through high-temperature oxidation via powdering the expanded graphite. After soaking the expanded graphite with styrene(S) and maleic anhydride(MA) monomers, the polymer (Poly(S-co-MA))/expanded graphite(EG) (PSMA/EG) composite granules were obtained by in situ polymerization. Light microscope，scanning electron microscope and X-ray diffraction characterization were performed. SEM analysis indicate that the expanded graphite was mostly tore to sheets with thickness of 50–80 nm and with diameter of 1μm. Optical micrographs showed that the distribution of graphite platelets is found to be nearly uniform.