The chemical compositions and characteristics of atmospheric aerosol over the South Yellow Sea and the East China Sea were investigated during spring (18 March to 9 April) and autumn (17 October to 5 November) in 2011. The water-soluble constituents (SO42-, NO3-, Cl-, Na+, Mg2+, K+, Ca2+, NH4+ and methanesulfonic acid, MSA) and metal elements (Al, Fe, Pb, Mn, Cu and Zn) were determined in total suspended particulate (TSP) aerosol samples from marine boundary layer. The TSP abundances ranged from 13.3 to 55.3 µg m-3 (average: 24.0 ± 10.3 µg m-3) and from 26.5 to 55.0 µg m-3 (average: 38.0 ± 8.2 µg m-3) during spring and autumn cruises, respectively. Secondary aerosol ions dominated the TSP aerosol composition, contributing 70.9% and 73.3% to the major water-soluble species collected during the two cruises, respectively. Principle component analysis presented the existence of four major sources (anthropogenic, crustal, sea salt and biomass burning) for aerosol species measured over the study oceanic regions. The average concentrations of MSA were 0.052 ± 7.7 and 0.041 ± 0.027 µg m-3 during spring and autumn, respectively, and the relative biogenic sulfur contributed to be 14.1% and 5.1% to the total non-sea-salt sulfate (nss-SO42-), suggesting the major contribution of anthropogenic source to sulfur budget over the study area. The acidic property was discovered in the aerosol samples. The averages of Cl- deficit were 31.1 ± 11.9% and 26.4 ± 11.3% in spring and autumn cruises, respectively, which might be caused by the reactions of sea-salt with acidic species like SO42- and NO3-. In addition, the total concentrations of determined metal species averaged 4.15 ± 1.09 and 4.79 ± 1.27 µg m-3 during the two cruises, respectively, accounting for 17.3% and 12.6% to the total TSP concentrations. In atmospheric aerosols, there was a clear seasonal variation in the dry deposition flux of the chemical components. Among them, the secondary inorganic ions deposition fluxes of NO3-, NH4+ and nss-SO42- were very large, accounting for 74.6% and 81.8% of the total deposition fluxes.