Abstract: Located in the Paleozoic uplift along the southern margin of Tu-Ha basin in eastern Xinjiang,the newly discovered Hongshan Cu-Au deposit occurs in the superim posed Mesozoic volcanic basin upon the north section of later Paleozoic Dananhu-Tousuquan accretionary arc.Kalatage Cu-Au orebelt is controlled by NWW-trend faults.The host rocks of Hongshan ore district are mainly rhyolitic-dacitic ignimbrites,whereas Cu-Au mineralization is closely related to quartz porphyry,rhyolitic porphyry and granitic porphyry.Mineralization styles are dominantly veinlet-disseminated and veinlet,occasionally stockwork.The mineral association is chalcopyrite,pyrite,bornite,chalcocite and sphalerite.Hongshan Cu-Au deposit,on the edge of the desert,is one of the driest areas in eastrn Tianshan.Oxidization zone of this depositlies on the upper part of primary sulfide orebodies which are dominant in sulfate minerals.Sulfurisotope analyses show that δ³⁴S values of pyrites vary in the range of +1.86‰～+5.69‰,with an average of 3.70‰,mostly in the range of +1.86‰～+3.20‰,and δ³⁴S_cp<δ³⁴S_py.Therefore ore-forming fluid of porphyry comes from mantle and was contaminated by the earth's crust.Sulfurisotope has reached balance in ore-forming process.