The invention relates to a three-section screw pressing forming device capable of automatically discharging drugs, and belongs to the field of screw pressing forming. According to the three-section screw pressing forming device, a screw pressing forming die comprises a feeding section die, a transition section die and a forming section die; a constant pressure hydraulic cylinder and thetransitionsection die are fixed to a left base with pulleys arranged at the bottom through a supporting plate, thefeeding section die is fixed to a right support after being in butt joint with a screw extruder,a guiding column fixed to a hydraulic cylinder supporting plate penetrates through guiding holes around a transition section supporting plate to be fixed with a feeding section supporting plate; theforming section die sleeves the guiding column between the hydraulic cylinder supporting plate and the transition section supporting plate through the supporting plate, and a supporting plate of the constant pressure hydraulic cylinder is connected with a supporting plate of the forming section die through a hydraulic cylinder, and a supporting plate of the transition section die is connected witha supporting plate of the feeding section die through a hydraulic cylinder. According to the three-section screw pressing forming device, the dies are not required to be removed when taking the drugs, the production efficiency is improved, the compactness of forming products is improved by pressing at the two ends of the screw pressing forming die, and screw pressing forming of drugs with the large sizes is realized.