Abstract: Systematic magnetic separation-demagnetization-combined activation reverse flotation desulfurization experiments were carried out on a magnetic concentrate with the iron grade of 55.61% and the sulfur grade of 3.81% whose main sulfide ores are pyrrhotite and pyrite. The test results showed that the sample was subjected to a weak magnetic separation test under the condition of grinding fineness -0.038 mm accounting for 88.32%. After demagnetization of the magnetic separation concentrates, the closed-circuit test of the whole process of "one-stage roughing, two -stage scavenging, three-stage cleaning and reverse flotation" was carried out with the pulp pH of 5.5 adjusted by sulfuric acid, compound activator of H₂C₂O₄+CuSO₄+Na₂S, and combined collector of the advanced xanthate (hydrocarbyl carbon number is 5-7) and the ammonium butyl aerofloat. The test finally obtained the iron concentrate grade of 66.71%, the iron recovery of81.57%, the sulfur content of 0.33%, and the by-product sulfur concentrate sulfur grade of 29.98%. The study better solved the actual production problems of the mine.