Taking water system of limestone-gypsum Wet Flue Gas Desulfurization (WFGD) device as object of study. First, this paper carries on the analysis to the quality of desulfurization wastewater, then in view of the water quality characteristic of desulfurization wastewater the paper proposes the materialized treatment method, and conducts the experimental study. In the materialized method selecting polymeric aluminum ferric silicate sulfate (PAFSS) as the coagulant, then using the orthogonal experiments determine PAFS best text condition under remove of the sulfide, the fluoride and the COD by PAFSS: the pH value 8~9,PAFSS throwing content 20ml/l, PAM throwing content 10ml/l, coagulation mixing time 25min, settling time 20min. Under the best test condition the treatment effect: after coagulation processing, sulfide elimination rate 99.3%; fluoride elimination rate 96.5%;COD elimination rate 78.5%. And the results achieve requests of GB 8978-1998" integrated wastewater discharge standard ".