CD values among Suzhou, Lin'an and Ningbo were relatively small, the CD values of Nanjing and Hangzhou with the other cities were both large, which demonstrated that the ion distributions were unanimous in Suzhou, Lin'an and Ningbo, and had large discrepancy for Hangzhou and Nanjing with other cities. This phenomenon was caused by the geographic locations and emission sources. Suzhou is near Taihu, Lin'an belongs to mountain area, Ningbo is coastal city, which all had great diffusion conditions and little anthropogenic pollution. Pollution sources from industry emission in Nanjing and vehicle emission in Hangzhou made their ion distributions greatly differ with other cities.It's belonged to ammonium-rich distribution in PM2.1 and ammonium-poor distribution in PM2.1e10 in the YRD region. The impacts of temperature on mass concentrations of NO3 and NH4þ in PM2.1 were greater than those in PM2.1e10. PCA modal shows that the sources of WSIs dominant by anthropogenic sources, soil particles or falling dust, sea salt and burning process.