In order to study the pattern of regional transport of PM2.5 and its chemical components, we developed a transport matrix of PM2.5 and its chemical components from the 31provinces (source) to 333cities (receptor) by applying the Particulate Source Apportionment Technology (PSAT) of CAMx model. The regional contribution of ambient PM2.5 and its key components, such as primary PM, sulfate, nitrate, and ammonium, are identified and quantified at region, province, and city level. The results indicate significant contribution of regional transport to ambient PM2.5 pollution in key regions and typical cities in Jing-Jin-Ji area. 22%, 37%, 28%, and 14% of ambient PM2.5in Jin-Jing-Ji, Yangtze River Delta, Pearl River Delta, Chengdu-Chongqing area, respectively, is contributed by emissions from outside region. Regional transport of pollutants contributes to more than 45% of annual average PM2.5 concentration in some provinces such as Hainan, Shanghai, Jiangsu, Zhejiang, Jilin and Jiangxi, and contributes to 37%, 42% and 33% of annual average PM2.5 concentration in Beijing, Tianjin, and Shijiazhuang City.