The invention provides a method for improving the ore separation index of copper-nickel sulfide ore containing talc, and belongs to the technical field of ore separation. The method comprises the steps that the copper-nickel sulfide ore with gangue mainly being the talc is ground fine, regulator sulfuric acid is added to adjust the pH of ore pulp to be 5-6, a certain quantity of micro-size fraction serpentine minerals are added for stirring and size mixing, and then a small amount of locust bean gum as an inhibitor, butyl xanthate as a collector and 2# oil as a foaming agent are added for flotation. By utilization of the gathering function of the micro-size fraction serpentine minerals and the talc of the gangue mineral, the hydrophilic serpentine is adsorbed on the surface of the hydrophobic talc, so that the surface of the talc is hydrophilic, and high-efficiency separation of the low-grade copper-nickel sulfide ore containing the talc is achieved. When the method treats the low-grade copper-nickel sulfide ore containing the talc, the separation index is good, the concentrate grade and recovery rate are both high, the waste serpentine minerals are used as the inhibitors, the dosage of chemical agents is reduced, and the method is a stable, efficient and environment-friendly copper-nickel sulfide ore separation method.