In the present invention, a method and system for equalizing and matching lithium secondary batteries belong to the field of secondary batteries. A lithium secondary battery is divided into more than one grade according to the magnitude of a consumable current Ic, the number of grades is h, the lithium secondary battery is divided into grades corresponding to the consumable current according to the magnitude of a voltage difference ΔV, a battery cell at a grade same as that of the consumable current and the voltage difference is selected for matching, so the range of the consumable current of the battery group can be controlled. The battery system configured in the method of the present invention converts consumable current grading into voltage difference grading after laying, so as to be convenient and swift; the range of the consumable current of the battery cell, the laying time, the equalization charging period, the equalization current, and the charger cutoff current are all under control, and are matched with each other, the equalization cost is low, and the charging equalization time is short; the laying service life and the maintenance period of the battery group can be designed or predicted during matching, and how many times of charging/discharging is required to charge the battery group to be balanced after the battery group is laid for an extremely long time is estimated in advance; the battery group reject rate is reduced, and the battery group reliability is improved.