The invention discloses a screw toothed molded line structure. The toothed molded line consists of a tooth-crest circular arc, an oval arc line, a transition curve and a tooth-root circular arc, whichare continuous, wherein the tooth-crest circular arc is connected with the transition curve through the oval arc line; and the long radius and the short radius of an oval are determined according tothe curvature of the tooth-crest circular arc and the curvature of the transition curve. The transition curve adopts an envelope curve of the oval arc line to replace the original cycloid curve, so that engagement for screws is contact between arc surfaces, and the problem that point contact is liable to wear is radically solved; meanwhile, the curvature of the oval arc line continuously changes on the whole arc line, so that the curvature of each of the transition curve, the circular arc and the tooth-crest top circle at two contact points continuously changes, transition is stable when the screw is in contact type engagement, vibrations and noises are avoided, and abrasion when the screw operates is greatly reduced, and therefore, the service life of a screw pump is prolonged.