Abstract: Pseudo-Glow Discharge was used to modify the surface of cotton fabric to improve the hydrophobicicty by using hexafluoropropylene (C3F6) as the monomer and helium (He) as the carrier gas at atmospheric pressure. Effects of discharge time, power, concentration and other conditions to the water repellency were investigated. It shows that the wetting time was mainly determined by the coverage of settled layer. The water contact angle of the treated sample can reach up to 130° and the wetting time is more than 120min after the cotton fabric is treated. The durability of the water repellency of the treated samples was tested. The chemical structure of the cotton fabric surface was characterized by XPS, ATR–IR and the result shows that F-contained groups has been introduced on the cotton surface and the settled layer has a Polyhexafluoropropylene like structrue.