To understand the mass size distribution of inorganic nitrogen (NH4 + -N、NO3 - -N、NO2 — N),one of the important nutrient of atmospheric deposition,the particle samples were collected by a AN-200 cascade impactor in Qingdao during July 2005 to March 2006.The mass size distribution of the particulates and the concentration of inorganic nitrogen components were obtained using IC (Iron Chromatography).The size distribution of particles shows double peaks,with the higher peak in the ‘accumulation mode’ and the lower one in ‘coarse mode’.