Abstract: A screw comprises a head, a shank disposed at one end of the head and provided with two inclined surfaces at a distal end thereof, at a joint of the inclined surfaces is formed an inclined reaming edge, at least one thread wound around a lateral surface of the shank and a positioning tip disposed at a middle section of the reaming edge. The positioning tip of the screw is firstly abutted against an object to be locked, so as to fix the screw to the object to be locked and prevent the screw from swinging. And then, the reaming edge of the shank performs the reaming operation in the object to be locked, and finally the thread performs cutting and locking operations, which can reduce the extruded material around the locking hole and prevent the object from being ruptured or deformed.