Abstract: The dynamic characteristics of atmospheric transport equation of air pollutants are analyzed by the scale analysis in this paper.Six important dynamic parameters showing the relative importance of dynamic,physical and chemical processes in atmospheric pollution are proposed originally.Their size of order of magnitude is analyzed for sulfur as an example.Especially,the importance of three sink mechanisms(chemical transfer,dry deposition and wet removal)in process of at mospheric pollution for different scale is discussed.Results show that the role of the gas chemical reaction for sulfur is less than the deposition and wet removal in general situation.The role of dry deposition is much dependent on the thickness chosen for the lowest layer of atmospheric model of air pollution.The wet removal process is important in general when it rains.Based on the analysis of the order of magnitude for the characters of terms in atmospheric pollution equation,we obtain the zero-and first order approximation equation which control the at mospheric transport process of air pollutant s(SOx).Their basic characters are also discussed.