Abstract: Glycerol-plasticized thermoplastic starch(GPTPS) and glycerol-plasticized thermopl-astic dry starches(GPTPDS-1 and GPTPDS-2) were prepared through a twin-screw extruder. Plasticity of the three were compared by X-ray diffraction(XRD), thermal gravimetric analysis(TGA), differential scanning calorimetry(DSC), and scanning electron microscope (SEM), to study the effect of pre-dry treatment on their plasticity. The results indicated, compared with native starch, TPS with lower crystallinity can be produced from dry starch in the presence of close amount of plasticizers; the temperature of extrusion should be under 170℃, andwithin the extrusion temperature range, the thermal stability of GPTPS is higher than that of GPTPD S- 2, while GPTPD S- 1 has the lowest thermal stability.