Abstract: How the flow responds to the various type of surface inhomogeneity is an important problem in micrometeorology. In this study a two-dimensional non-hydrostatic numerical model is developed to predict the spatial structure and variation characteristics of the flow over inland water body. The results show that when air flows over an inland water body, the pulse changes in surface roughness result in the formation of two internal boundary layers, which meet to the leeward shore of the water body, forming a "tonque" like spatial distribution The larger the land surface roughness, the larger the change of velocity of the ait folw over the inland water body will be. Atmospheric stability affects the change substantially, causing diurnal and seasonal changes in it.