Abstract: By theoretical analysis,the concept of relative index and frequency of pollution intensity is introduced in this paper, so that meteorological factors and the feedback from the distribution of pollution sources can comprehensively be considered. It is pointed out that the new-added pollution source should be located in the direction of city in which relative frequency of pollution intensity is the minimum, because the influence of air pollution on city is minimum in this condition. This concept has been applied in the master plan stage of Anqing city and more satisfied result has been gotten.