In order to study on the characteristics of chemical compositions and the sources of the atmospheric particles in Pearl River Delta Region (PRD), particle samples were collected with cascade impactor (8 classes) from the atmosphere in the Mt. Dinghu, the atmospheric baseline monitoring station of PRD region, during the autumn ( from Oct. to Dec.) of 2008, in Guangdong Province. Water soluble ionic concentrations were analyzed in the different size particles. The results were indicated as following: ①The highest concentration of SO42- and NH4+ appeared mainly when the fine particles with the size under 1.1μm. And highest concentrations of Na+ and Cl- were within the particles size of 1.1-2.1μm; ②The concentration of NO3- and K+ that were two modes with the higher concentration at 1.1-2.1μm, 3.3-4.7μm and 0.65-1.1μm, 5.8-9μm, respectively; ③The concentration of Ca2+ and Mg2+ presented mainly within coarse particles with the peak at more than 9μm.