Abstract: In this article the influence of heat treatment on the structure and properties of rigid polyether sulforne chain has been investigated thzoughly.It was found that the glass transition temperature of the material increases nd an unusual endothermic peak appears in the transition region when is thermal-treated at a preferable temperature under its Tg(200℃).With the aid of a new designed thermal stress apparatus(TSA)we found that during the course of post-elongation recovery,plastic defermation takes place and there is almost no elastic recovery after releasing of external force for untreated sample which has the similar behavior to that of polystyrene,a typical amorphous polymeric material.However,elastic defermation takes place and there is almost no permanent set after releasing of external force for thermal-treated sample which has the similar behavior to PET,on crystallin polymeric material.The result of Electron-microscopy investigation indicates that polyether sul-fone has a new order stucture because the two phase morphology with different contrast appears in the bright field picturs and clear diffraction cycles appear in the constiucncy electron diffraction diagram.In this article the influence of heat treatment on the structure and properties of rigid polyether sulforne chain has been investigated thzoughly.It was found that the glass transition temperature of the material increases nd an unusual endothermic peak appears in the transition region when is thermal-treated at a preferable temperature under its Tg(200℃).With the aid of a new designed thermal stress apparatus(TSA)we found that during the course of post-elongation recovery,plastic defermation takes place and there is almost no elastic recovery after releasing of external force for untreated sample which has the similar behavior to that of polystyrene,a typical amorphous polymeric material.However,elastic defermation takes place and there is almost no permanent set after releasing of external force for thermal-treated sample which has the similar behavior to PET,on crystallin polymeric material.The result of Electron-microscopy investigation indicates that polyether sul-fone has a new order stucture because the two phase morphology with different contrast appears in the bright field picturs and clear diffraction cycles appear in the constiucncy electron diffraction diagram.