Manufacturing method of square battery

The invention relates to a manufacturing method of a square battery, which comprises the following steps: a preparation process: winding and butting steel plates to manufacture a square tube shell; cutting the cathode cover plate and the anode cover plate; an assembling process: fixing a negative electrode cover plate with one end of the square tube shell, installing a negative electrode bracket in the square tube shell, overlapping negative electrode lugs of the electrode group into two groups and butting, assembling the butted electrode group into the square tube shell, and fixing the negative electrode cover plate and the negative electrode lugs; sealing, namely connecting the positive pole and the positive connecting piece, overlapping the positive lugs of the pole group into one group, fixing the positive lugs and the positive connecting piece, integrally fixing the positive connecting piece, the positive bracket, the positive cover plate and the insulating plastic part through the positive pole, and joi