Abstract: This paper proposes a scheme for the utilization of sludge from the FGD wastewater treatment system (desulfurization sludge) according to the characteristics of flue gas desulphurization (FGD) wastewater and the "triple box" process, The phosphorus removal technology on desulphurization sludge is studied using the simulated wastewater as the processing object. Effects of the sludge dosage and its calcium content on phosphorus removal efficiency are discussed, and the mechanism is explored with the study on adsorption thermodynamics and kinetics. The results show that phosphorus removal using calcium-containing sludge is mainly realized through chemical reaction and adsorption, and the product is CaHPO₄·2H₂O. The phosphorus removal rate is over 99% under a certain sludge concentration and calcium content. The higher the calcium content in the sludge, the greater the adsorption capacity for phosphorus and the less the sludge demand will be. In addition, the appropriate raising temperature can promote the adsorption of phosphorus to the sludge. The characterization analysis of X ray diffraction (XRD) and the scanning electron microscope (SEM) show that calcium phosphate rocks generate on the surface of the sludge, which further verifies the experimental results.