In this article a numerical approach has been developed to simulate the ZnO growth carried in a vertical reactor by metal-organic chemical vapor deposition (MOCVD). The coupled transport equations are solved numerically by employing the control-volume-based finite difference method. A three-dimensional model is put forward to analyze the deposition process. Simulations show that the deposition rate decreases with the substrate temperatures ranging between 500 and 700 degrees C. Substrate rotation and large density of the inject nozzles are found to favor significantly improvements on the film uniformity. Computational results show the same general features with the experiment data, which shows that the developed numerical technique is suitable for the simulation and optimization of the MOCVD reactor and could shed some light on the practical growth of ZnO for optoelectric device applications. (c) 2007 American Vacuum Society.