Abstract: The leaching of copper from the tailings of refractory copper oxide ore which comes from Tangdan in Yunnan Province in China by aqueous ammonium chloride/ ammonia solutions has been studied.The results show that leaching time，the temperature, the concentration of ammonium chloride and ammonia，the solid-to-liquid ratio， the amount of the Oxidant，additional order of the oxidant，oxidation time have favorable influence on the leaching ratio of copper oxide ores. The optimum leaching conditions are found to be: 10/1 liquid-to-solid ratio, 40 ℃, adding to H₂O₂（2.5 mL/g）, after 2 hours，then add to（NH₄）₂CO₃ and NH₃·H₂O, c(NH+₄)=3.2 mol/L, c(NH₃)=0.8 mol/L，continue reacting 4 hours. More than 72.3% of copper was effectively recovered.

Key words: Oxide copper, leaching tailings, Ammonia-Ammonium Carbonate, leaching