The effect of incident angle on dissociation probability is analyzed by Molecular Dynamics (MD) method. Hydrogen is used as the gas molecule and Pt(111) is used as the surface. The embedded atom method (EAM) is used as the interaction potential between the gas molecule and the Pt(111) surface. Initially, the effect of motion of atoms or molecules (dynamic effects) on dissociation probability is discussed. It shows that dynamic effects on the dissociation phenomena are very large at top site. MD simulations of D 2 molecules impinging on a Pt(111) surface are also carried out, changing the incident angle and its effects are analyzed. The results are also compared to those obtained by the molecular beam experiments to check the validity of the simulations. Consequently the results show that the dependence of translational energy and incident angle on dissociation probability roughly agree to those of experiments.