This study was designed to pinpoint the effect of salinity (NaCl and Na₂SO₄, add at salinity levels of 0~5%, respectively) on the species distribution of exogenous Hg (II) in wastewater-irrigated areas of Tianjin City. The fractions distribution of mercury in the studied fluvo-aquic soils were investigated by a modified Tessier scheme of sequential extraction procedures (SEPs), which detected with a quantitative analytical method and an isotopic ²⁰²Hg labeling method, respectively. Furthermore, the pools of isotopically exchangeable Hg (E-value) in soils which used as indictor of content of soil available Hg were also calculated based on the isotope ratios of R_Hg (²⁰²Hg/²⁰⁰Hg). It was showed that after amendments of exogenous ²⁰²Hg in salt-amended soils, isotope ratios of R_Hg (²⁰²Hg/²⁰⁰Hg) significantly varied in exchangeable (including water-soluble), fulvic acid and humic acid fractions, while barely changed in the fractions of carbonate, Fe/Mn oxides, organic, and residual species. It was also found that by comparison of the control without salt amendment, NaCl spiked to soils resulted in the more movement of exogenous ²⁰²Hg toward more instable fractions, including water exchangeable and fulvic acid fractions, while the distribution of exogenous Hg speciation in soils was not significantly influenced by Na₂SO₄. The content of isotopic exchangeable fraction (E-value) in 5% NaCl-amended soil increased by 51% compared with that in the control soil. E-value as a function of Cl^-1content in soil could be simulated by linear model (lnE = 0.0961lnCl + 4.895, n = 7, R² = 0.918). The study manifested that NaCl can significantly increase migration of Hg(II) in the soil irrigated with wastewater, which may enhance Hg(II) bioavailability in the soil and cause a hazard to surface water. Especially, it will be harmful to human body through the food chain.