A simple and environmentally friendly method was proposed to prepare high barrier graphene oxide nanosheet (GONS)/poly(vinyl alcohol) (PVA) nanocomposite films. Transmission electrical microscope and two-dimensional wide angle X-ray diffraction techniques showed that GONSs in PVA matrix were fully exfoliated, uniformly dispersed and highly oriented along the surface of nanocomposite films. Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) measurements investigated the strong H-bonding interactions between GONSs and PVA matrix. A remarkable improvement on barrier properties of GONS/PVA nanocomposite films was achieved. Both O₂ and water vapor permeability coefficients of PVA film declined by about 98% and 68% at a low GONS loading of 0.72vol%. This was attributed to excellent impermeable property of GONSs, their full exfoliation, uniform dispersion and high alignment in the PVA matrix and the strong interfacial adhesion between GONSs and PVA matrix. These results demonstrate that such a plate-like nanofiller blending method is an effective strategy to design and fabricate high barrier polymer-based nanocomposite films and it will dramatically promote the application of polymer film in the packaging industry.