Expanded graphite,prepared from the rapid heating of graphite intercalated compound,was blended with polystyrene via the intercalation and the in situ polymerization of styrene.SEM,STM and etc were used to characterize the nanostructure of the expanded graphite the composite of polymer/expanded graphite,and the changes of the nanostructure during the rolling process.The graphite formed the nanostructure during the expanding process of the GIC.The nanosheets were confirmed to have been dispersed in polystyrene matrix with the thickness of 10~30 nm.The conductivity of PS/expanded graphite composite was sensitive to the rolling process.The intensive rolling caused great decrease in its conductivity,due to the destruction of conducting network.