The invention discloses a method for separating and recovering a positive electrode active material in a lithium ion battery, which comprises the following steps: (1) after discharging a waste lithiumion battery, disassembling the discharged waste lithium ion battery, and collecting a positive electrode sheet; 2) pulverize that positive electrode sheet and sieving to obtain aluminum foil particleand black powder; 3) uniformly mix that black powder and the polar solvent, and react under the condition of heating or no heating to obtain a mixed slurry; 4) carry out magnetic separation on that mixed slurry to respectively obtain a magnetic slurry and a non-magnetic slurry; 5) recover that solvent of the magnetic slurry to obtain a positive electrode active material; (6) returning the non-magnetic slurry to the step (3) for use in place of the polar solvent, and after at least one recycling, recovering the solvent to obtain a mixture of the binder and the conductive carbon black. The method of the invention solves the problem of difficult filtration in the positive electrode material recovery process caused by the existence of the binder, and also enables the binder and the polar solvent for dissolving the binder to be recycled.