The ratio of the hydrophobic to hydrophilic species and their distribution on mineral surfaces significantly influences the floatability of sulfide minerals. Through the flotation test, the influence of different reagents on pyrite flotation was examined. The interaction mechanisms between copper xanthate and pyrite were evaluated using advanced analysis technologies, including contact angle measurements, zeta potential analysis, scanning electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The results show that the butyl xanthate in solution reacts with copper sulfate to form cupric xanthate, increasing the consumption of the collector butyl xanthate and resulting in lower floatability of pyrite. Cupric xanthate can be adsorbed on the pyrite surface through bonding with the sulfur sites. The adsorbed cupric xanthate on the pyrite surface undergoes redox reaction. The cupric xanthate is reduced to cuprous xanthate, and the sulfur on the surface will be oxidized. The adsorption products on the pyrite surface contain both cuprous xanthate and cupric xanthate. As the pH of a solution increases, the absolute value of the zeta potential of pyrite surface increased and the surface contact angle increased. Iron xanthate is also formed on the pyrite surface through a chemical reaction between the xanthate ions and pyrite, oxidation of xanthate ions to dixanthogen also takes place. Cuprous xanthate is the main hydrophobic substance on the pyrite surface, which can change the surface electrical properties and wettability of pyrite, and improve hydrophobicity of pyrite.