Abstract: Graphite nanosheets (nano-Gs) were prepared via sonication and then activated with mixed acid, finally the nano-Gs/PVC composites were prepared by way of melt blending. The structure of nano-Gs was characterized by FTIR and SEM, and the impact of nano-Gs on the conductive and mechanical properties of nano-Gs/PVC composites was also studied. The FTIR spectra demonstrate that the surface-active functional groups of nano-Gs increase significantly after mixed acid treatment, which form a certain degree of hydrogen bonding with PVC molecular chains. The SEM micrographs show that nano-Gs have a thickness ranging 30-80 nm and a diameter ranging 4-20 μm, and disperse randomly in PVC resin matrix. The electrical performance testing indicates that with the increase of the filled nano-Gs, the volume resistivity of the nano-Gs/PVC composites decreases nonlinearly and reachs the lowest value of 10³Ω·cm when the mass fraction of nano-Gs reachs its percolation threshold (10%). The mechanics performance testing shows that with the increase of the filled nano-Gs, both the tensile strength and notched impact strength of the composites increase first and then decrease, when the mass fraction of nano-Gs is 1%, the tensile strength and notched impact strength achieve the maximal value simultaneously and increase by 14% and 38% respectively compared with the pure PVC.