Abstract: Thermoplastic starch (TPS) was prepared by twin-screw extruder with benzophenone as a photoinitiator and glycerin as a plasticizer, and the effect of UV irradiation time on the mechanical properties, dynamic thermo-mechanical properties, thermal stabilities and water resistance of the resulting TPS were investigated. The results indicated that an optimum crosslinked network structure was formed with UV irradiation for 15 min, which led to an effective enhancement in mechanical properties and water resistance. The tensile strength, bending strength and impact strength of TPS were 4.57 MPa, 7.1 MPa, 69.39 kJ/m2, respectively, and its storage modulus was also improved. Moreover, the glass transition temperature reached a maximum value at this condition with a Tβ of -35.63 ℃ and a Tα of 53.96 ℃. The peak temperature of TPS corresponding to the maximum decomposition rate increased from 317.81 ℃ to 330.48 ℃, and its contact angle increased from 42.3 ° to 77.2 °, indicating the water resistance and water absorption of TPS were improved effectively.