Particle optics model for one-dimentional atom lithography is optimized with Monte-Carlo method. The initial condition of each trajectory is stochastically selected . The effects of isotope, longitudinal velocity distribution and transverse Gaussian divergence are systematically evaluated. Optimized model is compared with original model and the surface growth effect is described qualitatively. Excellent agreement is seen between numerical simulation and experiment under different laser powers. Furthermore, the effect of detuning is also discussed. It is found that good result can be obtained when the detuning is 250×2π MHz. The model presented takes all the factors into consideration and it provides better theoretical guide for current experiment.