The invention relates to a lithium ion secondary battery, in particular to a sorting method based on an alternating-current impedance spectrum. The method comprises the steps of (1) acquiring the alternating-current impedance spectrum; (2) analyzing equivalent-circuit parameters; and (3) conducting statistic analysis on the equivalent-circuit parameters. In the method provided by the invention, an electrode structure inside a battery system can be detected without damaging a battery, the inner information such as health condition of the battery, the electrolyte concentration, diaphragms and SEI (Solid Electrolyte Interface) membranes are accurately reflected; and according to the information, the coefficient of concordance is calculated by utilizing the principle of statistics, so that the consistency of the inner structure of the sorted battery can be ensured sufficiently, the differences of the sorted batteries are reduced obviously, and the defects of a sorting method in prior arts can be overcome.