Gaussian type models have limitations on predicting a detailed description of the near flow and pollution leads over complex terrains under neutral atmospheric conditions. Also, most models used recently have lack of ability to include atmospheric reactions. The model based on the numerical solution of the time-averaged Navier-Stokes equations and conservation equations needs to be developed to improve the limitations mentioned above. When the model was applied to the Shihwa area where the tracer experiment had been carried out, the simulation results have a great difference from the experimental results. There are two reasons that make the difference between the results by the model and the experiment. First, the Shihwa area is not a complex terrain. Second, meteorological data is insufficient. Therefore, the model should be applied to predict the dispersion of air pollutants over complex terrain rather than flat terrain in order that the model could be verified because the model was developed for the prediction of the dispersion over a complex terrain.