Abstract: Developing efficient non-lime inhibitors for iron sulfide minerals is a crucial research direction in the field of sulfide ores flotation. This study investigated the flotation characteristics of monoclinic pyrrhotite and examined the effects of three oxidants on its flotation behavior. The interaction mechanism between potassium permanganate oxidant and monoclinic pyrrhotite was elucidated using flotation kinetics, adsorption tests, and X-ray photoelectron spectroscopy (XPS). Flotation experiments demonstrated that the addition of a small amount of potassium permanganate exhibited a superior inhibitory effect on monoclinic pyrrhotite across a wide pH range compared to the high-alkali lime system, reducing the flotation recovery to as low as 6.23%. XPS analysis revealed that after treatment with potassium permanganate, the binding energies of multiple characteristic peaks for Fe 2p and S 2p on the monoclinic pyrrhotite surface exhibited significant shifts. Additionally, the relative sulfur content and the sulfur-to-iron ratio decreased markedly. It was inferred that surface oxidation led to the formation of abundant hydrophilic products, such as Fe(OH)₃, SO₄^2-, and ferrous sulfate hydrates. These products substantially weakened the adsorption of collector, resulting in a significant reduction in both the flotation rate and the recovery of monoclinic pyrrhotite.