The invention relates to a lead storage battery which comprises a plurality of unit cells, wherein the unit cells comprise polar plate groups, electrolyte and unit cell chambers; the polar plate groups and the electrolyte are stored in the unit cell chambers; the polar plate groups are formed by alternately arranging a plurality of positive plates and a plurality of negative plates under the separation of partition plates; the positive plates comprise positive current collectors with positive pole lugs, and positive active material layers kept by the positive current collectors; the negative plates comprise negative current collectors with negative pole lugs, and negative active material layers kept by the negative current collectors; the lead storage battery is characterized in that at least one of positive busbars and negative busbars of the unit cells has the following structure: the width A of a part, farthest from a pole, of the busbar is larger than the width B of a part, closest to the pole, of the busbar, namely, A is greater than B. By virtue of the lead storage battery, the welding performance of the busbars in a cast-on strap (COS) process is improved, and the discharge property is improved.