The invention relates to the field of banded extruders, and particularly relates to a three-screw banded extruder. The three-screw banded extruder comprises a rack, a charging bucket, a discharge opening, screw rods, a mixed extrusion box, a gear box and a driving motor, wherein the driving motor is installed on the right upper end of the rack, the gear box is installed in the middle of the upper end of the rack, the mixed extrusion box is installed on the left upper end of the rack, the screw rods are installed in the mixed extrusion box, the charging bucket is installed on the upper end of the mixed extrusion box, the discharge opening is formed in the left side of the mixed extrusion box, the driving motor is connected with the gear box by virtue of a rotating shaft, and the rotating shaft of the gear box is connected with the screw rods in the mixed extrusion box. Blades of the screw rods on both sides are designed into a herringbone shape, so that materials can be effectively prevented from overflowing from a feed opening in the upper surface and from clamping on both sides of a box body. According to the device, the screw rods can be simply and rapidly removed to be maintained and cleaned conveniently and completely, a cantilever is designed, so as to guarantee that the front ends of the screw rods cannot sink, and the service life of a bearing is prolonged; the screw pitch and the screw depth of a main screw rod are changed from large to small, so that the feeding is rapid, and the work efficiency is high.