The generalized stacking fault (GSF) energy curves for (111) surface of fcc metals are calculated by the second nearest-neighbor modified embedded atom method (2NN-MEAM), in order to investigate the deformation mechanism of (111) surface. Except the energy reduce for all these metals, strange energy curves are found for Au, Pd and Pt, especially for Au. Combining the surface GSF energy data and the experimental results, we find that the deformation mechanism should be explained by not only the values of the stable stacking fault energy γ sf and unstable stacking fault energy γ usf , but the whole shape of a metal’s energy curve.