The equipment used for the plasma treatment of poly(ethylene terephthalate) fiber was a capacitively coupled flow system supplied by a 13.56MHz power source. The volume of this reactor was 2035ml, and experiments were carried out at pressures ranging from 1.0 to 2.0 Torr in an air plasma. The alkali treatment was performed with 30% NaOH aqueous solution at 50°C.It was possible to produce samples with the same weight loss by choosing suitable conditions for each method. Comparing the samples with the same weight loss prepared by both methods, the plasma treated fabric was thicker, stiffer and stronger than that treated by the alkali solution. When samples treated by the different methods had the same stiffness, the thickness and tensile strength were also the same. The surface morphology observed by SEM was too rough with alkali treatment, and the gloss disappeared. On the other hand, the plasma-treated surface was almost as smooth and glossy as the untreated sample. The wettability was remarkably improved by air plasma even for short treatment time. From the ESCA measurements, the improved wettability is considered to be due to the increase of oxygen content of the fabric surface.Finally, it is clear that the air-plasma treatment is an alternative good method to the alkali process for improving the quality of the PET fabrics. In addition, the plasma treatment did not deteriorate the appearance of the fabric as did the alkali process.