The limestone-gypsum wet flue gas desulfurization (WFGD) process has a significant influence on the emission characteristics of soluble ions in particulates. In this study, a simulated limestone-gypsum WFGD platform was used to study the emission characteristics of water-soluble ions in flue gas after desulfurization. The experimental results indicated that the entrainment of desulfurization slurry droplets was the main source of water-soluble ions emission while water-soluble ions cannot be carried by vaporous water in flue gas. The limestone-gypsum desulfurization process can form soluble ionic particles with particle size less than 1 mu m. In addition to Ca2+, Mg2+, SO42-, and Cl-, which were the main ion components in the slurry, NH4+ was also the main ion composition of the soluble ionic particles, indicating that the entrainment and evaporation of slurry droplets and condensation of volatile components were the formation mechanism of the soluble ionic particles. Reducing the gas velocity and liquid-gas ratio was beneficial to weakening the entrainment of the desulfurization slurry droplets, thereby reducing the discharge of soluble ionic particles and water-soluble ions. Besides this, with the decline of the slurry concentration and flue gas temperature, the soluble ionic particles level emitted from desulfurization process also decreased.