[en] Highlights: • The geometry of H-adatoms on VG was studied by DFT method. • The H-pairing decorating on VG induced half-metallicity behavior in graphene. • The C-atoms at vacancy dominated the electronic and magnetic properties in graphene. We studied the electronic structure and magnetism in graphene induced by vacancy-defect and hydrogen-pairing adatoms using density functional theory (DFT). The results indicated that the decorating of H-adatoms brought half-metallicity behaviors in graphene, which depended on the configurations with the different number of carbon atoms between the adsorption sites of H-adatoms. When the number is odd, the systems exhibited half-metallic. Furthermore, the PDOS results suggested that the electronic and magnetic properties of graphene were mainly controlled by the C atoms around the vacancy-defect. These results provide useful information to understand the modifying of the electronic structures in hydrogenated graphene.