We present an experimental study on the resolution of inkjet-printed fine patterns deposited on polyimide substrate. We are particularly concerned with the effect of plasma surface polymerization on the drop diameter and uniformity deposited on the substrate. DOE (Design of Experiments) technique was used to investigate the statistically significant variables among five process variables such as plasma power, gas pressure, process time, gap between electrodes, and temperature. For PI substrate, we generated the 2nd-order response surface model from which we can find out the optimum condition to minimize the pattern resolution as well as the effect of each variable. From the surface analysis, we also found that as the amount of fluorine functional group on the surface increases, the hydrophobicity increases while the surface energy decreases, resulting in improving the resolution.