In this paper, formation of zinc sulfide species during roasting of ZnO with FeS₂ was investigated and its contribution on flotation was illustrated. The evolution process, phase and crystal growth were investigated by thermogravimetry (TG), X-Ray diffraction (XRD) along with thermodynamic calculation and scanning electron microscopy-Energy-dispersive X-ray spectroscopy (SEM-EDS), respectively, to interpret the formation mechanism of ZnS species. It was found that ZnS was initially generated at about 450 °C and then the reaction prevailed at about 600 °C. The generated Fe_xS would dissolve into ZnS and then form (Zn, Fe)S compound in form of Fe₂Zn₃S₅ when temperature increased to about 750 °C. This obviously accelerated ZnS phase formation and growth. In addition, it was known that increasing of ZnO dosage had few effects on the decomposition behavior of FeS₂. Then, flotation tests of different zinc oxide materials before and after treatment were performed to further confirm that the flotation performances of the treated materials could be obviously improved. Finally, a scheme diagram was proposed to regular its application to mineral processing. It was systematically illustrated that different types of ZnS species needed to be synthetized when sulfidization roasting-flotation process was carried out to treat zinc oxide materials.