The invention relates to the technical field of toilet paper production, and discloses an automatic roll paper cutting device. The automatic roll paper cutting device comprises a large roll paper roller, a first roll paper roller, a second roll paper roller, an outer gear ring, a sun gear, a first planet wheel and a second planet wheel; an air cylinder is connected to the outer gear ring through a connecting rod, a motor is connected to the sun gear, the first planet wheel and the second planet wheel are both meshed with the outer gear ring and the sun gear at the same time, the first roll paper roller is connected with the first planet wheel, and the second roll paper roller is connected with the second planet wheel; the first roll paper roller is provided with a pushing rod connected with a suction ventilator, the first roll paper roller and the pushing rod are both hollow, a groove is formed in the first roll paper roller, an air suction hole is formed in the groove, a cutter is arranged in the first roll paper roller, a rotating rod is connected to the cutter and arranged in the pushing rod, and a rotating handle is arranged on the rotating rod; and a cutter outlet is further formed in the first roll paper roller, and the structure of the second roll paper roller and the structure of the first roll paper roller are completely the same. By means of the automatic roll paper cutting device, automatic rolling again can be achieved, and manual traction is not needed.