Based on our recently developed reactive force field, we studied dissociative dynamics of H-2 molecule on Pd (111) surface with vacancy and step. The results show that vacancy results in a little higher probability than perfect surface. Further analysis shows that vacancy can hinder the diffusion of H-2 molecule in the dissociation dynamics. Moreover, it is found that the probability of step is higher than that of perfect surface but it is insensitive to the height of step. The roles played by the direct dissociation at high energy and bond counting mechanism at low energy are discussed. (C) 2012 Elsevier B. V. All rights reserved.