Abstract: The complex network was used to investigate PM_2.5 of the air pollution. The relevant data of PM_2.5 were analyzed with correlation and the complex network in regions in china was established. Through the study of the degree, community structure and motif, the results showed that the main polluted cities in China could be effectively analyzed by this method, and the air polluted cities having cluster phenomena needed to be treated as a whole, which was consistent with real conditions. Because of the fluidity of the air, this research provides guidance for analyzing the agglomeration of polluted cities.