The water-cooled internal screw conveyor comprises a feed unit, a discharge unit, a barrel, a cooling unit, a drive unit and a support unit; the feed unit and the discharge unit are respectively arranged at both ends of the barrel; the drive unit causes the barrel to rotate about its central axis of symmetry; the support unit supports the barrel; the barrel comprises an outer barrel and an inner barrel; a jacket of a certain length is provided on the outer circumference of the outer barrel adjacent to the feed unit, The cooling unit comprises an inlet pipe situated at the centre of the discharge unit; a hollow spiral blade located within the inner barrel and connected to the inlet pipe; an outlet pipe situated at the centre of the feed unit and connected to the hollow spiral blade; and hollow baffle plates or a second hollow spiral blade situated within the jacket of a certain length.