Abstract:  The composition of desulfurization slurry is complex due to the recycling utilization of the slurry, in particular the halogen elements are easy to accumulate in the slurry and  difficult to be removed. Oxidated mercury is water soluble and is easy to be removed by wet flue gas desulfurization (WFGD) system, however, the absorbed mercury in the desulfurization slurry has the problem of secondary release. Therefore, the influence of halogen elements on Hg emission in WFGD system was systematically studied in the lab-scale by on-line monitoring and the influence of reaction temperature, halogen species, halogen concentrations, and reaction pH  on mercury release were investigated. The mechanism of mercury emission behavior was also simulated. The results indicate that the mercury emission is inhibited by halogen elements in the increasing order of Cl