The utility model relates to a connecting device for power batteries and belongs to the technical field of power batteries. The connecting device comprises the power batteries, the positive pole of each power battery is led out through a positive pole column arranged on the upper end face, and a battery body (3) of the power battery serves as a negative pole. The connecting device is characterized by comprising thread tightening devices and connecting pieces (5), wherein the thread tightening devices are fixed on the upper end face and the lower end face of the power battery and used for letting an upper power battery and a lower power battery be in series connection to be a battery pack, and the connecting pieces (5) are matched with the thread tightening devices to achieve the series connection of two columns of battery packs. Through the connecting device for the power batteries, the power batteries are in series connection in a threaded mode to form the battery pack, the shortcomings during the welded connection in the prior art are overcome, dropping and stripping do not occur easily, and the reliability is high. The connecting device has the advantages of being convenient to dismantle and install; and especially when some power battery in the battery pack is subject to faults and needs to be replaced, the power battery can be replaced very conveniently.