Abstract: The electrochemical mechanism of sphalerite, particularly in strong alkaline media, was studied by cyclic voltammetry.It was shown that the element S can be oxidated to SO₄^2- on sphalerite in strong alkaline media, which was helpful to bring about self-oxidation inhibitation for sphalerite and reduce the dosage of inhibitors for priority galena flotation, which could attain the effects of restrain zinc while floating lead.Meanwhile, the sphalerite which was activated by CuSO₄ can be flotated in KBX solution at pH=11.0(Eh<0.2V), and the suitable dosage of CuSO₄ was about 2×10^-4mol·dm^-3.This technology has been applied successfully in potential-control flotation of complex lead-zinc-iron sulfide mines in Huili.