The aim of the study was to achieve the reduction characteristic of vacuum annealed graphene oxide paper, and to provide an effective reduction method for preparing flexible graphene paper functional materials. The graphene oxide papers were reduced by vacuum annealing with different temperatures. Oxygenous groups and their percentages in reduced graphene oxide papers were analyzed by X-ray photoelectron spectroscopy. Crystalline quality of the reduced graphene oxide papers was characterized by X-ray diffraction and Raman spectrum. High resistance meter and four probe meter were used to measure the specific resistance of the reduced graphene oxide papers. From all above, evolutions of oxygenous groups, crystalline quality and specific resistance with annealing temperature were studied. The major oxygenous group in graphene oxide paper, epoxy group, can be removed by vacuum annealing at 200 ℃, which resulted in significant decrease of the specific resistance. When the Graphene oxide paper was vacuum-annealed below 600 ℃, the oxygenous groups would be interacted remarkably to form carbonyl groups and atomic vacancy defects. Carbonyl and carboxyl groups at defect edges would be removed primarily at temperatures between 600~1000 ℃. Meanwhile, the crystalline quality would get worse as a consequence of large lattice holes generated by etching atomic vacancies. The graphene can be recrystallized to mend defects and restore sp2 phase by vacuum annealing at 1200 ℃. However, there were still a small number of oxygenous groups existing in the reduced graphene oxide paper annealed at 1200 ℃, and the crystalline quality and specific resistance were not as good as the corresponding values of graphite. The results show that vacuum annealing is an effective method to reduce graphene oxide paper. Good reduction characteristic can be achieved by vacuum annealing above 1000 ℃. In order to obtain reduced graphene oxide paper to an extreme, it is necessary to further increase the vacuum annealing temperature or develop enhanced reduction methods at lower temperatures.