This study was carried out to investigate the microstructure and physical property of PET POY which was taut-annealed under various conditions. The DSC melting curves of annealed PET POY showed double melting peaks in most cases. As temperature and time increased, form II crystal became sharp and increased in size, and form I crystal decreased in size. The slower the heating rate, the higher the programmed heating effect during DSC analysis. Crystallinity and briefringence of annealed specimens increased as the treatment temperature and time increased. Breaking tenacity of specimens treated for 3 minutes increased as the treatment temperature increased, but others decreased. Elongation at break decreased as the annealing temperature and time increased. Dye uptake of annealed specimens decreased as the temperature increased up to $190^{circ}C~210^{circ}C$. then the uptakes increased at higher temperatures. At the same temperature, dye uptake of the specimen decreased as time increased.