Aerosol emission has been the bottleneck problem for the development of ammonia flue gas desulfurization. In this paper, aerosol properties were investigated on-line. Experiments on the effect of different desulfurization phases, oxidation degree and pH value of desulfurization liquid and the analysis of the aerosol formation were carried out. As the results show, aerosols are mainly submicron particles ranging from 0.1μm to 0.4μm. NH4HSO4 and NH4HSO3 exist during the initial phase of desulfurization, while (NH4)2SO4 and (NH4)2SO3 are the main part when the system is in good running. Without oxidation of desulfurization liquid, the aerosol compositions are mainly SO32- and the amount of SO42- increases significantly after oxidation. The amount of SO32- increases when the pH value of desulfurization liquid gets higher. NH4HSO4 and NH4HSO3 exist in the aerosols formed by the heterogeneous reaction which makes greater contribution to the aerosol formation and the compositions of aerosols formed by entrainment and evaporation of desulfurization
