The composites of thermoplastic starch plasticized by urea and formamide/citric acid-activated montmorillonite (UFTPS/CMMT) were prepared by the method of melt-interealation The ratio of urea and formamide used was 2：1 Wide angle X-ray diffraction (WAXD)

transmission electron microscope (TEM) studies revealed that UFTPS was intercalated into the layers of CMMT successfully and formed composites with CMMT．When the CMMT content was 2 wt％～10 wt％．after the composites had been stored at a reletive humidity of 50％ for 10 days

the mechanical testing indicated that the maximum tensile strength of the composites reached 24.86 MPa

and the tensile strain reached 134.50％．Youngs modulus increased from 87.25 MPa for pure UFTPS to 625.25 MPa for UFTPS/CMMT composites．and the breaking energy increased from 1.87 N·m to 2.45 N·m

which showed that mechanical properties of composites were evidently better than those of UFTPS. Rheology analysis illustrated that during the process of composite preparation both the extruder screw speed and the processing temperature could effectively aajust the flow behavior of composites．Comparing with traditional GTPS

the composites greatly reduced the recrystallization resulting from long time storing．In contrast to pure UFTPS．the composites had better water resistance and thermal stability.