Abstract: In view of the present situation of desulfurization wastewater pretreatment technologies, the boundary conditions of the application of tubular microfiltration membrane combined with chemical precipitation softening process for treatment of desulfurization wastewater were studied. The pilot test results showed that the hardness ions and suspended solids concentration had different effects on water flux of tubular microfiltration membrane. The influent Ca²⁺ concentration had little influence on water flux of tubular microfiltration membrane when its concentration was less than 6000 mg/L. When the influent Mg²⁺ concentration exceeded 800 mg/L or the suspended matter concentration exceeded 70,000 mg/L, the water flux of tubular microfiltration membrane decreased rapidly and the operation became unstable. The main reason for rapid decrease of membrane flux was that Mg（OH）₂ particles blocked the membrane pores. In the continuous operation test, the concentrations of influent Mg²⁺ and suspended solids were controlled below 800 and 70,000 mg/L respectively. The turbidity index of the water produced by tubular microfiltration membrane met the requirements of reverse osmosis influent, and the flux was stable and higher than 2000 LMH. The results can provide design and operation guidance for the engineering application of tubular microfiltration membrane in treatment of desulfurization wastewater from power plants.