As ore grades constantly decline, more copper tailings, which still contain a considerable amount of unrecovered copper, are expec-ted to be produced as a byproduct of froth flotation. This research reveals the occurrence mechanism of copper minerals in typical copper sulf-ide tailings using quantitative mineral liberation analysis (MLA) integrated with scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS). A comprehensive mineralogical characterization was carried out, and the results showed that almost all copper minerals were highly disseminated within coarse gangue particles, except for 9.2wt％ chalcopyrite that occurred in the 160–180 μm size fraction. The pre-dominant copper-bearing mineral was chalcopyrite, which was closely intergrown with orthoclase and muscovite rather than quartz. The flota-tion tailings sample still contained 3.28wt％ liberated chalcopyrite and 3.13wt％ liberated bornite because of their extremely fine granularity. The SEM–EDS analysis further demonstrated that copper minerals mainly occurred as fine dispersed and fully enclosed structures in gangue minerals. The information obtained from this research could offer useful references for recovering residual copper from flotation tailings.