Abstract: Thermoplastic starch (TPS) was prepared by extrusion and then injection molded into the test bars. The ethanol solution containing benzophenone was coated on the surface of TPS and the irradiated by UV light. The effect of UV irradiation time on the mechanical performance, dynamic thermomechanical properties and water resistance of TPS was investigated intensively. The results indicated that an optimum cross-linked network structure was formed with UV irradiation for 15 min, which led to an effective improvement in mechanical properties and water resistance. In this case, the resulting TPS achieved the maximum tensile strength of 5.28 MPa as well as the flexural strength of 5.83 MPa and impact strength of 73.99 kJ/m2. Moreover, the TPS presented two loss factor peaks at -45.40 and 60.60 ℃ with an improved storage modulus, and it also exhibited the highest surface contact angle of 96.8 °.