The invention discloses a method for increasing the copper and nickel recycling rate from copper-nickel sulfide ore flotation middlings. The technical problems that, the copper-nickel sulfide ore middling circulation amount is large, floatability is poor, and recycling is hard can be solved, meanwhile, the adverse effect of magnesium-containing silicate to flotation of copper-nickel sulfide ore can be lowered, the content of magnesium oxide in concentrate and the usage amount of inhibitor are reduced, and the copper and nickel recycling rate is increased. In the copper-nickel sulfide ore flotation process, selective acid leaching magnesium removing treatment is carried out on the middlings (scavenging concentrate and cleaner tailings) in the copper-nickel sulfide ore through acid adding under the normal temperature and the normal pressure, and therefore the circulation number of middlings floating hardly is reduced, and the adverse effect of magnesium-containing silicate on flotation of copper-nickel sulfide ore is lowered. After leaching is finished, flotation is carried out on leaching residues, the copper and nickel recycling rate is increased, and foam products obtained through two times of flotation are combined to serve as low-grade concentrate. The method is reasonable in technology and simple in process, and industrial implementation is easy.