Abstract: In order to realize the zero-discharge treatment of desulfurization wastewater gradually,a set of desulfurization wastewater pretreatment process system is built and put into operation in a power plant in Guangdong province,which adopts the“double alkali softening+tubular ultrafiltration”treatment process and after treatment,the wastewater can directly enter into the subsequent zero-discharge treatment system of the whole plant.The operation performance of desulfurization wastewater pretreatment system is monitored and analyzed,and the results show that the control of the process parameters of double alkali softening is poor,mainly manifested as unstable p H control and unreasonable dosage of soda ash,and the concentration rate of tubular ultrafiltration is far from sufficient.The softening parameters are optimized by double alkali method and the experimental results show that when the p H is above10.90 and the alkali ash dosing ratio reaches 1.1,the effluent quality can meet the subsequent water intake requirements of the whole plant wastewater zero-discharge treatment system.Through material balance analysis,the inlet flow rate,sludge discharge flow rate and water production flow in the tubular ultrafiltration process unit should be about 9 m~3/h,2 m~3/h and 7 m~3/h respectively to maximize the concentration ratio.After operation performance monitoring analysis and optimization study,the operation efficiency of desulfurization wastewater pretreatment system is improved,and the operation cost is reduced.