In this paper, a 3-D Monte Carlo model for NiTi alloy thin film growth on square lattice substrate is presented. The model is based on the description of the phenomenon in terms of adsorption, diffusion and re- evaporation of different atoms on the substrate surface. In this article, multi-body NiTi potential is used to calculate diffusion activation energy. The energy which is related to the types of the atoms is equal to the total energy change of the system before and after the diffusion process happens. The simulations serve the purpose of investigation of the role of diffusion in the determination of the microstructure ofthe alloy clusters. The effects of the substrate temperature and the deposition rate on the morphology ofthe island are also presented. The island size distribution and roughness evolution have been computed and compared with our experimental results. (C) 2014 Elsevier B.V. All rights reserved.