PET fabrics were hydrolyzed with NaOH solution after plasma treatment. The surface physicochemical changes and weight loss, according to the various conditions of plasma treatment (gas, power, pressure, and time), were investigated. From surface tension and ESCA analysis, it appeared that reactive gas $(O_2,;air)$ plasma treatment introduced more polar groups on the PET surface than non-reactive gas (argon) plasma treatment. Also, the polar group contents was decreased by heat treatment. The etching effect of 0$_2$and air in plasma treatment was greater than that of argon. Weight loss rate in alkaline hydrolysis after argon plasma treatment was much higher than that of $O_2$and air plasma treatment. Heat treatment after 0$_2$and air plasma treatment increased the weight loss rate in alkaline hydrolysis.