In this paper, we use the density functional theory to study the adsorption of mercury on the surface of intact, defective and doped graphene respectively. The results show that the adsorption energies of the elemental mercury on the intact and defective graphene surface are -0.220 ev and -0.342 ev, which belongs to physisorption process; while the energy on the surface of Al-doped graphene is -0.57 ev, which is a chemisorption process. Besides, the adsorption energy of Hg atom on the doped graphene surface grows as the number of Al atom grows. However, when increasing the number of Al-doped on the defective position, the adsorption of Hg will be affected. The best number of Al-doped on the single defective site is one. (C) 2017 Elsevier B.V. All rights reserved.