A refractory zinc ore, distinguished by its high magnesium content and low grade, was found to contain valuable elements, primarily zinc and cadmium, with concentrations of 1.60% and 50.60 g/t, respectively, predominantly hosted within marmatite. The principal impurities in the ore were identified as SiO₂ and MgO, with concentrations of 37.66% and 34.47%, respectively. The gangue minerals were primarily composed of serpentine, pyroxene, amphibole, and chlorite, with marmatite exhibiting a complex paragenetic relationship with these magnesium-bearing gangue minerals. To effectively mitigate the adverse effects of high serpentine content on zinc flotation performance, a series of systematic single-factor flotation condition tests were conducted. The interaction mechanism between a combined reagent of C6H8O7+(NaPO3)6 and serpentine was analyzed using infrared spectroscopy. Additionally, changes in the elemental composition and morphological characteristics on the surface of marmatite, both before and after treatment with C6H8O7+(NaPO3)6, were meticulously examined using scanning electron microscopy and energy dispersive spectroscopy(SEM-EDS). The optimal technical parameters for the roughing flotation stage were ascertained through experimental investigations. These parameters comprised a grinding fineness of 75.23% passing 0.075 mm, a C6H8O7 dosage of 600 g/t, a (NaPO3)6 dosage of 800 g/t, a CuSO4 dosage of 500 g/t, a butyl xanthate dosage of 120 g/t, and a No.2 oil dosage of 24 g/t. Utilizing a closed-circuit flotation flowsheet characterized by “one roughing, two scavenging, and two cleaning stages, with middlings sequentially returned to the preceding stage”, a final zinc concentrate was effectively produced. This concentrate exhibited an assay of 48.52% Zn, 1 400×10-6 Cd, and 1.92% MgO, with respective recoveries of 89.47% for zinc, 84.20% for cadmium, and 0.16% for magnesium oxide. Infrared spectroscopy analysis indicated that the interaction with the C6H8O7+(NaPO3)6 reagent system resulted in the emergence of two new distinct absorption peaks on the serpentine surface. The observed spectroscopic features were identified as the C=O and P=O stretching vibration peaks. Simultaneously, the Mg-O out-of-plane vibration peak exhibited a shift from its initial position at 567 cm-1 to 546 cm-1. These spectroscopic alterations suggest that the reagent combination likely adsorbs onto the serpentine surface through complexation. Further corroboration was provided by SEM-EDS analysis, which revealed that post-treatment with C6H8O7+(NaPO3)6, elements such as O, Mg, and Si were no longer detectable on the marmatite surface. Notably, the marmatite surface was predominantly devoid of adhering serpentine particles. This compelling evidence indicates that the application of C6H8O7+(NaPO3)6 effectively mitigates hetero-coagulation between serpentine and marmatite, thereby significantly enhancing the selectivity of the flotation process.