The invention relates to a device for automatically spot welding a battery pack electrode, comprising a battery conveying mechanism, a metal connection sheet conveying mechanism and a spot welding machine. The battery conveying mechanism performs stepping motion at given intervals. The metal connection sheet conveys the metal connection sheets for the corresponding battery electrode in the same frequency with the stepping motion of the battery conveying mechanism. The spot welding machine spot welds the battery electrode in the same frequency with the stepping motion of the battery conveying mechanism. The battery conveying mechanism comprises a bottom plate, a clamping plate, a first cylinder and a second cylinder. The battery is arranged on the bottom plate. The first cylinder drives the clamping plate to clamp the battery. The second cylinder drives the clamping plate to move the given interval distance towards the advancing direction of the production line. Then the first cylinder drives the clamping plate again to loose the battery. The second cylinder drives the clamping plate (19) to return to the original position towards the reverse direction of the production line. The invention can greatly improve the production efficiency, simultaneously improve the finished product rate of the spot welding.