Abstract: Coal combustionprocess causes As release and As can migrate to gypsum when entering the wet flue gas desulfurization (WFGD) system.It is of great significance to get a better understanding on the partitioning and species of As in a WFGD system. The partitioning and species of As in a WFGD system are determined by high performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS) technique. In addition,the mineral composition and chemical composition in the process of gypsum production are characterized by X-ray diffraction (XRD) and X-ray fluorescence (XRF),respectively. The results show that the main mineral composition in gypsum sampleis gypsum,the main chemical composition are CaO and SO₃,and the total content of which is in the range 89.97%-95.34%. The concentration of As in limestone is 1. 30 μg/g with As (Ⅲ) accounting for 24%.As (Ⅲ) can be oxidized by forced oxidation process resulting As (Ⅲ)proportion 10% decrease. A small amount of As is transported to gypsum,which contribute to the separation function from the hydrocyclone. The concentration of As in gypsum is determined as 1.28 μg/g where the proportion of As (Ⅲ) and As(Ⅴ) are 14%and 86%,respectively. The concentration of As in the solid fraction and liquid fraction of desulfurization effluent are 8.3 μg/g and 0.006 μg/L,respectively.Nearly all the As in solid fraction is removed by effluent treatment process,andalso 16.7%of As in liquid fraction is removed,resulting in that the As concentration in desulfurization effluent is over 4-5 times higher than that in gypsum. An enrichment of As in desulfurization effluent treatment process is addressed,whereAs concentration in neutralization tank,precipitation tank,and flocculation tank are 5.96,6.13 and 6.70 μg/g,respectively. Most As in this product is determined as As(Ⅴ) with proportion over 87%.As is strongly enriched in wet electrostatic precipitators (WESP) ash,where As(V)is predominant existence as residual form and is difficult to leach to the environment.