Abstract: A low-grade oxidized copper ore, with high oxidation ratio and high combination ratio and serious weathering, can not effectively been separated by the conventional sulphidizing flotation process. Therefore, water-heating sulphidization flotation process was adopted to deal with the oxidized copper ore. That is S-2 by disproportionation reaction of sulfur in autoclave, will transform oxidized copper ore into copper sulfide, and then the product, copper sulfide minerals,were separated by the conventional flotation process. Experimental results indicate that the optimal conditions for water-heating sulphidizing process are determined as follows: reaction temperature 200 ℃，reaction time 180 min, particle size 90% -0.074 mm, vulcanizing agent dosage 1.4 times to the theoretical dosage, liquid-solid ratio was 1.4. Compared with the conventional sulphidizing flotation with Na₂S, the grade and recovery rate of copper concentrate obtained in these conditions were 15.73% and 71.49%, and increased by 4.28 and 38.73 percentage points，respectively.

Key words: Refractory oxidized copper ore, Water-heating sulphidization, Floatation