A Monte Carlo model for simulation of the 3-Dimension growth of Ag thin film on the amorphous Si substrate is presented. Three principal dynamic processes for each atom are considered in the description of thin film growth: deposition, diffusion and re-evaporation. The diffusion activation energy calculated by many-body semiempirical potential is related to the positions of the atoms. It is equal to the energy difference between the total energy of the system before and after the diffusion. The influences of the substrate temperature and the deposition rate on the transitions of island morphologies in thin film growth at the initial stage have been studied in detailed. The results show that with the increase of the substrate temperature or the decrease of the deposition rate, the size of the island increases, and the number of islands decreases. There are two distinct stages captured by the model in island coalescence regime, which consistent with that of the experiment. (C) 2014 Elsevier B.V. All rights reserved.