Polyethylene terephthalate (PET) has been modified by Ag ion implantation with a dose range from 1×10 16 to 2×10 17 ions/cm 2 using a metal vapor vacuum arc source. The surface morphology was observed by atomic force microscopy. The Ag atom precipitation was determined. The change of the nano-structure of Ag-implanted PET was observed using a transmission electron microscope. It is believed that this change causes an improvement of the conductive properties and wear resistance. The electrical properties of PET were also changed after Ag ion implantation. The resistivity of implanted PET decreased with an increase in ion dose. When an Ag ion dose of 2×10 17/cm 2 was selected, the resistivity of PET could be less than 0.02 Ω m. The surface hardness and modulus increased compared to the untreated PET. The hardness and modulus of Ag-implanted PET with a dose of 2×10 17/cm 2 is 2.2 and 7.3 times greater than that of pristine PET, respectively. The area of a cutting groove for Ag-implanted PET is narrow and shallow compared to the unimplanted PET. Thus wear resistance improved greatly. The Ag ion beam modification mechanism of PET will be discussed.