The invention discloses a high-capacity battery sealing process. The high-capacity battery sealing process comprises the following steps of (1) arranging a shape of a cup to be a horn, wherein the inner diameter of a cup bottom is 9.95-10 millimeters, the wall thickness is 0.16-0.20 millimeter, the inner diameter of a cup mouth is 10.1-10.5 millimeters, the wall thickness is 0.16-0.20 millimeters,and the draft angle from the cup bottom to the cup mouth is 0.13-0.5 degree; (2) performing stitching on a battery cell after being sleeved with the cup, adding a medium, performing liquid injectionand top touch, and sealing by a special sealing die and a sealing clamp, wherein the external diameter of the sealing site does not exceed 10.20 millimeters; (3) sleeving the sealed battery with a special die with the inner diameter being 10.30 millimeters for size correction, correcting the external diameter of the whole battery to 10.30 millimeters; and (4) performing oil spraying on an inner wall in the die before the battery is sleeve so as to reduce a friction force between a cup wall and the inner wall of the die, the battery is easier to penetrate through the die and the damage of the inner wall of the die onto a nickel plating layer on a surface of the cup wall is simultaneously reduced.