In this research, we studied the dyeing properties of PET fibers in terms of TiO2 contents, fiber strength and spinning oil which may cause barre' effect. The effect of TiO2 contents in the fibers had no influence on the dye uptake. However, the reflectance(%) behaviors showed the different visual properties as TiO2 contents in the fibers. The other factors could be considered as strength and spinning oil which also revealed difference on the dye exhaustion. The experimental results showed that TiO2 contents within the fibers influenced reflectance(%) behaviors. Furthermore, fiber strength and spinning oil could be considered other major factors to impart the dyeing irregularity and barre' effect.