Abstract: Malachite, as a typical copper oxide ore, exhibits strong hydrophilicity and consequently poor flotation recovery. In this study, sulfidation roasting is proposed as a pretreatment strategy to improve the flotation efficiency of malachite. Pyrite was employed as the sulfidation agent during roasting. Thermodynamic calculations verified the feasibility of the sulfidation reactions. Microflotation experiments demonstrated that the flotation recovery of malachite increased by nearly 70% compared to the untreated sample. X-ray diffraction (XRD) analysis showed that malachite decomposed into CuO during roasting and mainly formed CuS and Cu2S after sulfidation. This finding was further supported by X-ray photoelectron spectroscopy (XPS) analysis, which revealed the presence of sulfur species in different oxidation states (S2-, S22- and Sₙ²⁻) and copper species as both Cu+ and Cu2+ on the surface of the roasted sample, along with a notable decrease in oxygen content. Additionally, the formation of copper sulfides disrupted the original porous structure, leading to a significant reduction in internal pore size. The contact angle measurements indicated that the hydrophobicity of malachite improved markedly, with the angle increasing from 43.71° to 93.89° after sulfidation roasting. Zeta potential results further indicated increased surface electronegativity caused by sulfur species adsorption. Overall, sulfidation roasting using pyrite significantly improved the floatability of malachite by generating hydrophobic copper sulfides on the mineral surface, demonstrating its potential as an effective pretreatment for copper oxide ores.