A battery and a battery cover assembly thereof are provided. The battery cover assembly comprises a cover (1) having a through hole; an extraction electrode terminal (3); and an insulating seal member disposed between the cover and the extraction electrode terminal. The extraction electrode terminal (3), starting from its top, includes a columnar seal part (31), a position part (32) and a weld part (33) that are consecutively connected together, the columnar seal part (31) passing through the through hole of the cover and having a seal groove formed along a circumferential surface thereof, the position part (32) having a horizontally-oriented platform, and the weld part (33) having a sheet-like shape and being perpendicular to the horizontally-oriented platform of the position part.