Abstract: Based on the analysis of the effect of diffusional anisotropy,dimer and dimer row,a kinetic Monte Carlo（KMC） model was developed to investigate the intial stage of homoepitaxy on Si（100）-（2×1） surface.The results showed that the diffusion distance follows an exponential temperature dependence,i.e.L=L₀Ae^T/C.There is an optimum islanding temperature at a given deposition rate and this temperature increases with increasing deposition rate.The film growth changes from disperse mode to compact mode and the diffusional anisotropy is more distinct with the decrease of deposition rate.