Abstract: In this paper the author uses CAPPS model system to make simulation experiments.It aims at studying the influence of dustpan-shaped ferrain on dilution and diffusion of main pollutants such as SO2,NOx and PM10 in Taiyuan City under the control of different circulations.The results showed thatin the emulated orographic scheme,controled by local scale circulation,the dustpan-shaped terrain inhibited dilution and diffusion of main polutants and aggravated the air pollution in ground layer;while controlled by large scale circulation and was a southerly or easterly wind in ground layer,the dust pan-shaped terrain dilution and diffusion of main pollutants and the density of main pollutants decreased,but when there was a northerly or westerly wind in ground layer and wind speed ≥5 m/s,the density of SO2 and NOx decreased and the density of PM10 increased sharply.As a result,in the emulated orographic scheme,influenced by large scale circulation,the dust pan-shaped terrain promotes vertical motion.The higher the terrain,the more obvious the increase.