Abstract: Poly(vinyl alcohol) (PVA) films with moisture content（1.85%MC and 41.33%MC） were exposed to atmospheric pressure plasma jet（APPJ）. The surface morphology changes of the films were observed with SEM. Chemical changes and crystalline structures were analyzed with FTIR, XPS and XRD. The results showed that the existence of water significantly increased the etching and oxidation effect during He/O2 plasma treatment. The etching rate could reach 0.68μm/min and oxygen content increased from 30.8% to 34.8%. Meanwhile, the degree of crystallinity was enhanced by 48%.

Key words: Atmospheric pressure plasma, Moisture, Polyvinyl alcohol, Surface morphology