The similarity in floatability between molybdenite (MoS₂) and galena (PbS) poses a significant challenge for the efficient separation of these minerals in mineral processing. Regarding this issue, the current research systematically evaluates the selective inhibition effect and interfacial regulation mechanism of maleic acid–acrylic acid copolymer (MLA), a green and environmentally friendly inhibitor, in a kerosene-based flotation system. Through a series of comprehensive experimental investigations - including single-mineral and artificial mixed-mineral micro-flotation tests, contact angle measurements, Fourier transform infrared spectroscopy (FTIR) analysis, and X-ray photoelectron spectroscopy (XPS) analysis - the differential adsorption behavior of MLA on these two minerals has been clearly elucidated. The experimental results show that under specific conditions - namely a pH of approximately 8, an MLA concentration of 8 mg/L, and a kerosene concentration of 30 mg/L -there is a significant difference in the flotation behavior of the two minerals. The recovery of galena decreases sharply from 89.13% to below 2%, whereas the recovery of molybdenite remains consistently above 95%. This result effectively achieves a high degree of separation selectivity between the two minerals. Contact angle measurements further indicate that MLA significantly enhances the hydrophilicity of the galena surface, while exerting negligible influence on molybdenite. In conclusion, this study clearly demonstrates that MLA acts as an effective inhibitor for galena and enables efficient recovery of molybdenite through selective coordination and precise regulation of interfacial wettability. These findings provide not only a solid theoretical foundation but also valuable practical guidance for the green flotation separation of complex sulfide mineral systems and the development of novel low-toxicity inhibitors. This research therefore makes a significant contribution to advancing mineral processing technology and promoting environmental sustainability in the mining industry.