Poly(ethylene terephthalate) (PET) fabrics were modified by treating with radio frequency (RF) plasma of different gases, including argon (Ar), nitrogen (N2), oxygen (O2) and sulfur hexafluoride (SF6), under varied power (50-150 watt) and time period (0.5-20 min). Observations indicated that plasma has affected the morphology and roughness of PET fiber surface in the nano-scale level. After plasma treatment, test patterns were printed by inkjet printer directly onto the sample surface. The enhancement of color printing performance on PET fabric by plasma treatment was evaluated by color spectroscopy. The surface nano-modified PET fabrics by Ar, N2, O2, and SF6 plasmas all exhibited enhanced color yield. AFM, SEM, FTIR-ATR and XPS results suggested that the improved pigment color yield was neither clearly contributed by the wettability of the fabrics nor the polar group induced onto the fiber surfaces but rather mainly by the alteration of surface roughness.