The invention provides a screw shaft structure for a screw conveyor, belonging to the technical field of material conveying equipment. A blade (2) is arranged on a screw shaft body (1) of the screw shaft structure for the screw conveyor, and consists of a blade assembly I (3) and a blade assembly II (4), the blade assembly I (3) is arranged as a structure protruding out of the surface of the screw shaft body (1), and the blade assembly II (4) is connected with the blade assembly I (3) through a connecting bolt (5). The screw shaft structure for the screw conveyor is simple, and low in manufacturing cost, only simple improvement is needed, the overall screw shaft is not needed to be changed in wear of the blade due to long-time working of the screw conveying, the stopping time of the screw conveyor can be effectively reduced, the wear of the blade can be effectively reduced, the service life of the blade can be prolonged, the usage rate can be increased, and the change intensity and maintenance cost are finally lowered.