The invention relates to the technical field of screws and provides a single-screw mechanism provided with a flow guide spiral groove. The single-screw mechanism provided with the flow guide spiral groove comprises a handle portion and a screw body. The screw body is provided with a threaded structure. The threaded structure is composed of a plurality of main screw flights. The main screw flights are distributed on the screw body and of a spiral structure. The main screw flights form the spiral groove on the main body. The surface of the screw body and the surfaces of the main screw flights are coated with a tungsten carbide coating. The screw body is hollow. Reinforcing ribs which are intersected in a cross manner are arranged in the screw body. The screw body comprises a feeding section, a compressing section and a discharging section. The screw outer diameters of the feeding section, the compressing section and the discharging section are gradually increased. Auxiliary screw flights are arranged besides the main screw flights on the compressing section. A spiral seal ring is arranged at the connection position between the handle portion and the screw body. The single-screw mechanism provided with the flow guide spiral groove has the beneficial effects of being high in wear resistance and corrosion resistance and long in service life and having good material conveying and plasticizing effects.