One of the most promising methods for surface property modification is electron beam irradiation, which can create new chemical groups on surfaces. In this study we investigated the surface functionalisation of polyethylene terephthalate (PET), a commonly used polymer material with many applications. The changes in surface properties were examined after electron beam irradiation with near edge X-ray adsorption fine structure (NEXAFS). The angle dependent NEXAFS spectra measured at the C K-edge of PET exhibit good directionality with a tilting angle α of 31.0°. As the duration of the electron beam irradiation is increased, new chemical bonding is induced on the surface and the angle dependence of PET disappears, which are results of the breaking of the C=C π* bonds.