The invention discloses a betel nut packaging bag opening device. The device comprises two racks, two bag suction units and two plastic bag retaining plates. The two bag suction units and the two plastic bag retaining plates are arranged on the rack, and the plastic bag retaining plates are disposed between the two bag suction units. Each of the two bag suction unit comprises a rotation disc, a rotation disc shaft, a sucker, a piston rod, a cam and a cam shaft. The rotation disc shafts are arranged on the rack, groove wheels and the rotation discs are arranged on the rotation disc shafts, and a plurality of piston cylinders are arranged at the ends of the rotation discs. The cam shafts are arranged on the rack, and the cams are arranged on the cam shafts. The suckers are arranged on the outer walls of the bottom of the piston rods, and the bottoms of the piston rods are communicated with the suckers. Springs are arranged between the pistons in the piston cylinders and the bottoms of the piston cylinders. Column rollers are arranged at the ends of the piston rods, and the column rollers of the piston rods are connected with the cams. By means of the device, the betel nut automatic packaging line opening process is achieved, the worker labor intensity is reduced greatly, and the worker labor environment is improved.