Improvement in synthetic fiber based composites is a hot topic in the material area. The incompatibility between the surfaces of synthetic fibers is a significant challenge due to fibers hydrophobic property. In this study, PET (polyethylene terephthalate) fibers based on low hydrophilic were slightly treated with NaOH or sodium dodecyl benzene sulfonate (SDBS). SEM images showed that there were some pits on the surface of PET fibers treated by NaOH, while PET fibers treated by SDBS became smoother. The peaks at 3725 cm-1 and 3628 cm-1 were generated for PET fibers treated by NaOH, which was attributed to —OH produced from the ester group hydrolysis, but no same peak is shown for the treated ones by SDBS. Meanwhile, the crystallinity indices of the treated PET fibers slightly decreased. Compared with original PET fibers, the formation of sheet made from PET fibers treated by NaOH became worse, but that from SDBS treated PET fibers became better.