Abstract: A copper-nickel sulfide ore has the problems of low flotation recovery and high magnesium content in concentrate. In order to optimize its flotation index，an optimization test was carried out. The results show that the addition of regulator BC can increase the floating speed of copper-nickel minerals and reduce the gangue inclusions in the foam. After adding the regulator BC in the closed-circuit test，the copper and nickel metal recovery rate increased from 78.72% and 80.88% to 81.68% and 85.37%，respectively，and the magnesium oxide grade in the concentrate decreased from 9.41% to 8.34%.

Key words: copper-nickel sulfide ore, flotation, regulator