Penetration depth of plasma surface modification of inkjet printing polyester fabrics was investigated. A four-layer stack of woven polyester fabrics was exposed to atmospheric pressure air plasma. Surface morphology and chemical compositions of each fabric layer in the stack were analysed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Wetting time was used to evaluate surface hydrophilicity on the top and bottom sides of each
fabric layer. It was found that the atmospheric pressure plasma was able to penetrate four layers of polyester fabrics and the effect weakened from the top down. The research of antibleeding property and colour strength reveals that the atmospheric pressure plasma could substantially penetrate two layers of polyester fabrics to observably improve their inkjet printing effect