To improve the analysis ability of residue levels of persistent toxic substances(PTS)in environ-ment,this paper investigated the distribution characteristics of air concentrations of polycyclic aromatic hydro-carbons(PAHs)during the Spring of 2007(January to April)in 4 different functional areas(urban,subur-ban,rural,and remote areas)in and near the Harbin metropolitan by using the fuzzy C-means clustering al-gorithm,and got the cluster centers of different samples and a membership matrix which offered quantity foun-dation for analysis of samples description.Results showed that the contamination level in the urban industrial area was the highest,followed by those in the other urban places and rural area,and the contamination levels in the remote area and in the places on the windward were the lowest.PAHs in Harbin urban atmospheric were mainly from coal-burning and industrial emissions,those in rural areas were mainly from the burning of crop stalks.PAHs in air in this region have imposed a potential threat on human health.