The invention discloses a method for separating a current collector from an active material of a lithium battery. The method comprises the following steps: (S1) dismantling an electrode of the lithium battery; (S2) immersing the electrode of the lithium battery into deionized water at 75-85 DEG C, simultaneously adding an anionic surfactant and a hydrochloric acid, and carrying out heat preservation and stirring for 4-6 hours, so as to obtain a reaction liquid a; and (S3) separating the current collector from the active material. The invention further provides an application of the method for separating the current collector from the active material of the lithium battery in a lithium battery production industry and a waste lithium battery recycling industry. The current collector can be quickly separated from the active material in the lithium battery; mechanical pulverization or high-temperature calcination on raw materials is not needed; reduction of energy consumption in production is facilitated; meanwhile, the current collector can be separated from the active material on the basis of keeping the structural integrity of the current collector; improvement of the recovery rate of the current collector is facilitated; and a metal component is prevented from being mixed into the active material.