The invention discloses a granule conveyor screw assembly, comprising a screw rod sleeved inside the hollow inner cavity of an external cylinder, and a discharging pipe installed at the lateral side at the top of the external cylinder; a feeding inlet arranged at the lateral side at the bottom of the external cylinder and a feeding pipe extending toward the exterior side of the feeding inlet installed at the lateral side at the bottom of the external cylinder; the screw rod comprises a shaft lever, and a thin rotary vane is wound at the lateral side of the shaft lever; and a thick rotary vaneis wound, or a cylinder is sleeved at the periphery of the bottom of the shaft lever and a thick rotary vane is wound at the periphery of the bottom of the shaft lever. Because of the thick rotary vane structure at the bottom of the shaft lever and the combination of the thick and the thin rotary vanes, the materials are enabled to enter the interior of the external cylinder from the feed pipe; and because of the height of the thick rotary vane wound around the shaft lever is larger than that of the upper edge of the feed inlet, the materials will not contact the thin rotary vane at the initial stage of entering the cavity of the outer cylinder. The granule conveyor screw assembly can prevent the materials from filling up the thin rotary vane at the upper part of the screw rod to extrude and damage the equipment; and can finish operation at a slow-speed of rotation and large elevation angle working conditions of the screw rod.