One of the principal problems in flotation of copper complex ores is the presence of pyrite and copper-activated pyrite in moderately alkaline pHs. Misreported pyrite into copper concentrates dramatically declines copper grade and its recovery. In this study, the effect of sodium sulfide, sodium metabisulfite (SMBS), and their dosages (100, 200, 300, and 400g/t) were investigated on chalcopyrite and pyrite floatabilities in a high pyritic copper sulfide ore. Furthermore, the role of particle size distribution (PSD) in three different levels (i.e., d(70), d(75), and d(80) of passing 75 mu m) was evaluated by a series of batch flotation experiments. It was revealed that using 200g/t SMBS provides not only the highest and the lowest chalcopyrite and pyrite recoveries, but also the maximum and minimum copper and iron grades. Pyrite recovery was sharply increased by the addition of sodium sulfide in light of sodium sulfide-induced collectorless flotation; however, it showed a very weak effect on chalcopyrite floatability. In addition, the highest and lowest chalcopyrite and pyrite recoveries were, respectively, identified when d(75) equaled to 70% 75 mu m. In other words, for the high pyritic copper ore type, it is feasible to achieve the highest chalcopyrite recovery consuming the lowest grinding energy.