In this paper, thiohexanamide (THA) surfactant was synthesized and introduced as a collector for sulphide ores. The flotation behavior of THA to sulphide ores was investigated by micro-flotation tests, bench-scale tests and adsorption quantity measurements. The results demonstrated that compared to O-isopropyl-N-ethyl-thionocarbamate (IPETC), THA exhibited superior selectivity to chalcopyrite against pyrite and galena. In comparison with another chalcopyrite collector sodium isobutyl xanthate (SIBX), THA showed stronger flotation affinity to chalcopyrite. UV/vis spectra results illustrated that THA can selectively reacted with Cu2+ than with Fe2+ or Pb2+. The adsorption mechanism of THA to chalcopyrite was evaluated by FTIR spectra, zeta potential measurements and XPS analysis. The conclusion was further confirmed by density functional theory (DFT) calculations. Two adsorption geometries were suggested, one with the formation of a four-membered ring complex, another with the connection between just Cu and S atoms.