The invention provides a package label attaching device. The package label attaching device comprises a label storage mechanism, a pressing mechanism, a label processing mechanism, a translation mechanism and a rack, wherein the rack comprises two vertical brackets which are arranged on the left and right sides and a cross beam between the two vertical brackets, the translation mechanism is arranged on the cross beam in a transverse direction, the label processing mechanism is perpendicularly arranged on the translation mechanism, the label storage mechanism is arranged on one side of the label processing mechanism, and the pressing mechanism is arranged on the cross beam below the label storage mechanism; the pressing mechanism is a label attaching cylinder; the translation mechanism is ascrew rod translation mechanism; and the label processing mechanism comprises a processing box body, tensioning devices, a label arrangement device and a feeding motor are arranged on the box body, the label arrangement device is arranged at the bottom of the box body, and the protruding end of the label arrangement device is over against the lower pressing part of the label attaching cylinder. Aplurality of tensioning rollers and tension adjusting devices are arranged, so that the tension of labels is adjusted, the labels are difficult to fold, and the tensioning effect is good.