PM 2.5 aerosols were collected in forests along north latitude in boreal-temperate, temperate, subtropical and tropical climatic zones in eastern China, i.e., Changbai Mountain Nature Reserve (CB), Dongping National Forest Park in Chongming Island (CM), Dinghu Mountain Nature Reserve (DH), Jianfengling Nature Reserve in Hainan Island (HN). The mass concentrations of PM 2.5 , organic carbon (OC), elemental carbon (EC), water soluble organic carbon (WSOC) as well as concentrations of ten inorganic ions (F − , Cl − , NO 3 − , SO 4 2− , C 2 O 4 2− , NH 4 + , Na + , K + , Ca 2+ , Mg 2+ ) were determined. Aerosol chemical mass closures were achieved. The 24-hr average concentrations of PM 2.5 were 38.8, 89.2, 30.4, 18 μg/m 3 at CB, CM, DH and HN, respectively. Organic matter and EC accounted for 21%–33% and 1.3%–2.3% of PM 2.5 mass, respectively. The sum of three dominant secondary ions (SO 4 2− , NO 3 − , NH 4 + ) accounted for 44%, 50%, 45% and 16% of local PM 2.5 mass at CB, CM, DH and HN, respectively. WSOC comprised 35%–65% of OC. The sources of PM 2.5 include especially important regional anthropogenic pollutions at Chinese forest areas.