The invention relates to an automatic feeding and discharging machine for cutting paper tubes. The automatic feeding and discharging machine comprises a machine base, a driving chamber, a rotating shaft and a cutting device. The rotating shaft further comprises a feeding and discharging device and a conveying device, the feeding and discharging device comprises a moving mechanism, a lifting mechanism and a clamping mechanism, and the conveying device comprises a supporting plate, a third motor, a driving wheel, a driven wheel and a belt. Through the conveying device, the paper tubes are constantly conveyed to space below clamping rings, the lifting mechanism drives the clamping rings to descend to the paper tubes, then the clamping mechanism drives the clamping rings to clamp the paper tubes, finally, the moving mechanism drives the clamping rings to clamp the paper tubes and insert the paper tubes into the rotating shaft, after cutting is completed, the clamping rings clamp the paper tube sections closest to the driving chamber, and the clamping rings are moved, so that all the paper tubes are pushed out of the rotating shaft. In the automatic feeding and discharging mode, potential safety hazards are eliminated, labor intensity is lowered, time is shortened, labor is saved, and influences on production efficiency are avoided.