Abstract: Temperature-sensitive textiles were prepared by plasma-induced graft polymerization of poly (N-isopropyl acrylamide) (PNIPAAm) hydrogel on PET fabrics. FT-IR shows the monomers were introduced onto the surfaces of the fabrics. The water permeability of the grafted PET fabrics showed a sharp change around the LCST. The relationship between the weight gain rates and the “switching effect” was investigated. When the weight gain rates is 20.1%, the best “switching effect” can be obtained.