Abstract: The influence of ethylenediamine tetraacetic acid disodium calcium (EDTA Na₂-Ca) on the flotability of smithsonite in the dodecylamine (DDA) cation flotation system was investigated by single-mineral flotation test. The results showed that EDTA Na₂-Ca could not collect smithsonite activated by sodium sulfide, but could enhance the collecting ability of DDA at pH 9.2~11.1. The better flotation performance could be achieved when the mixed collector with 40% mass ratio of DDA replaced by EDTA Na₂-Ca was used. The results of flotation solution chemical calculation, mineral dissolution tests, and dynamic potential tests showed that EDTA Na₂-Ca significantly improved the flotation recovery of smithsonite by promoting the dissolution of Zn²⁺ on the smithsonite surface and reducing the potential of the mineral surface.