In this report, the relaxation behavior of amorphous poly(ethylene terephthalate) (PET) in global chain orientation but nearly random segmental orientation (GOLR) state is studied by infrared dichroism, optical birefringence and hot shrinkage measurements at temperatures below or up PET＇s glass transition temperature, Tg. The results indicate that the difference in the relaxing rate between global chains and segments is at least in similar to 10(2) times order above PET＇s Tg (similar to 84 degrees C), with a rough approximation; while the sudden decrease of small Delta n of the sample (similar to 10(-4)) upon being treated at about 85 similar to 90 degrees C, implies us that the small Delta n is closely related with the orientation of global chains.