Abstract: Triton X-100 was used to improve the bioleaching of chalcopyrite with Acidithiobacillus ferrooxidans， and its effects on ferrous and sulfur oxidative activities of At.ferrooxidans and bioleaching of chalcopyrite were investigated. Chalcopyrite after bioleaching was characterized by XRD. Results showed that the addition of Triton X-100 has little negative effect on ferrous-oxidizing activity of At.ferrooxidans， but it is favorable for that of sulfur. The copper extraction yield of chalcopyrite with 30mg·L^-1 Triton X-100 increases by 52.15 % compared with the bioleaching without Triton X-100. The elemental sulfur produced during bioleaching of chalcopyrite is efficiently bio-oxidized and dissolved by At.ferrooxidans in the presence of Triton X-100， consequently increasing concentrations of the bacteria and ferric ion in bioleaching system， thus enhancing the oxidation and dissolution of chalcopyrite.

Key words: chalcopyrite, Triton X-100, Acidithiobacillus ferrooxidans, bioleaching, element sulfur