Abstract: Under the conditions of different chimney heights,different wind speeds and different atmospheric stabilities,the ground maximum concentration and its distance of SO2 were simulated by ISC3 model.Numerical simulation shows that under the conditions of constant chimney heights and constant atmospheric stabilities,the ground maximum concentration and its distance of SO2 decrease with the increase of wind speed.If chimney heights and wind speeds are constant,the ground maximum concentration and its distance of SO2 become smaller when atmospheric instability increases.Under the conditions of changeless wind speed and stability,the ground maximum concentration of SO2 increases and the ground maximum distance of SO2 keeps unchangeable with the decrease of chimney height.The chimney height should be built less than 300 m.