The applicability and reliability of the ONIOM framework in modeling metal surface were first examined in the present study. Both two- and three-layer ONIOM methodology are found economical and reliable. The first nearest coordinate metal atoms of those forming adsorption sites, which play a key role in determining the adsorption energies, are required to be described by an accurate high level method, while a low level method can be applied to the second nearest neighbor or farther atoms.