Abstract: The crystallinity of PVA film under different annealing condition was measured by X-ray diffraction in this paper. The H2 barrier property of PVA film under different annealing condition was also studied in the hydrogen gas permeation system. Increasing annealing temperature can increase the crystallinity of PVA film, so the hydrogen barrier permeability of the annealed PVA film will be better. But the annealing temperature should be selected under 180℃ to prevent the PVA film from thermal degradation. On the other side, annealing the PVA film under its glass transition temperature will also improve the hydrogen barrier permeability of the PVA film. Lower alcoholysis degree of PVA films show better H2 barrier property improvement after they are annealed under glass transition temperature.