The main disadvantages of the conventional thermoplastic starch (TPS) are the retrogradation

poor water resistance and unsatisfactory mechanical properties particularly under wet or dry environments．In this paper

formamide and urea were used as a mixed plasticizer to prepare urea／formamide-plasticized TPS(UFPTPS) with both the good mechanical properties and the good retrogradation resistance. FTIR analysis indicated that the micro-environments of the chemical groups in formamide-plasticized TPS(FPTPS) changed less than in glycerolplasticized TPS(GPTPS) during a period of 70 days. This was related to the fomation of more stable hydrogen bonds between formamide and starch. By Scanning Electron Microscope(SEM) the native cornstarch granules were proved to transfer to a continuous phase with the destruction of all crystallinity．The effect of water contents on the mechanical properties of UFPTPS was also studied

and UFPTPS had good ductility at water contents of 9％～34％．After being stored for one week at RH=33％

the tensile strength

elongation and energy at break of this TPS reached 4.83 MPa

104.6％ and 2.17 N·m

respectively. The influence of formamide and urea on the retrogradation of TPS was studied using X-ray diffractometry. It was found that the mixture of formamide and urea could effectively restrain the retrogradation and prevent urea from crystallization. On the other hand

both the thermal stability and water resistance of UFPTPS was better than those of TPS plasticized by each single plasticizer (including glycerol)．The TPS properties mentioned in this paper were ameliorated by the mixture of formamide and urea(10％／20％ weight based on starch)

mainly for it could form more strong and stable hydrogen bonds with starch hydroxy groups than glycerol could. As a novel plasticizer

the mixture of formamide and urea would be potential in extending the application scopes of TPS.