The invention provides a high-yield screw host driven by a low-rotary-speed high-torque AC motor, which comprises a feeding device, a screw extrusion device and an electric driving device, wherein the electric driving device drives the screw extrusion device to rotate, so that plastic particles supplied by the feeding device is extruded into plastic melt; and the motor is a torque motor. This invention solves the phenomena that the noise pollutes the environment and an extruder has more complex structure. Through the use of the torque motor, a reduction gearbox is not arranged in the extruder, and the noise produced by the extruder is low in the production process, so the impact of the extruder on the surrounding environment is little. In the absence of the reduction gearbox, the material for producing the reduction gearbox is saved; and simultaneously, the weight of the whole set of extruder is reduced, and the material is saved. Compared with an asynchronous motor, the torque motor saves the energy by 15 to 20%, increases the yield by 2.5 times, and reduces about 30 dB of noise.