Abstract: The acid leaching experiments for oxidized cobalt ore which from democratic republic of Congo （DRC） with 1.10% Co was carried out， and sodium sulfite was used as reducing agent. Effects of reducing agent， acid content， temperature， liquid-solid ratio and reaction time on the leaching behaviors were investigated. Results show that the most optimum conditions as follows: liquid-solid ratio 1.5， reaction temperature 70 ℃， reduction agent dosage is 1.8 times of theoretical amount， and the best reaction time was 2 h， under these conditions， the extraction efficiency of Co is as high as 94.86%， and Mn is 97.43%，Fe is 15.56%，Al is 42.53%，cobalt content in residue is 0.059%. The metallic minerals structure was dissociated during reducing leaching process， valuable metals get into solution as form of ions， and the selective leaching of minerals has been realized.

Key words: Oxidized ore, Reducing leaching, Cobalt, Leaching rate, Reaction mechanism