The electronic and magnetic properties of graphene functionalized by 4f-orbital RE-metal atoms (Ce, Nd, Sm and Eu) were investigated by the density functional theory (DFT) calculations. The results of binding energy and geometry parameters showed that the hollow site, the center of a carbon hexagon, was the most stable adsorption structure. Furthermore, the PDOS results suggested that the electronic hybridization between the RE-adatoms and C atoms was mainly contributed by the 5d orbitals, whereas the 4f-orbital of the metal adatoms dominated the net magnetic moments of the systems significantly.