Abstract: Thermoplastic starch plastics was prepared by using glycerol and sorbitol as plasticizers，and a single screw extrusion equipment with deep screw grooves, short pitch, and long shear zone was designed to enhance shear action and improve the mechanical properties of thermoplastic fullstarch plastics. The effects of strong shearing on the fullstarch plastics using scanning electron microscopy, infrared spectroscopy, thermal analysis, and Xray diffraction. It showed that the hydrogen bonds were formed between plasticizer and starch granules, the spherulite structure of the starch granule was destroyed, which made the starch form a homogeneous phase structure after extrusion. Compared with normal extrusion process, the material at break extruded by the newly designed extruder gave a better thermal stability, moreover, the tensile strength increased by 172 %, and the elongation at break decreased by 18 %.