The low-pressure high-frequency plasma chemical vapor deposition (CVD) system was developed with non-thermal plasma process to study the Polyethylene naphthalate (PEN) surface characteristics. Plasma surface treatment by oxygen can improve the adhesive properties. A mixture of Ar and O-2 gas was used in the plasma treatment. The oxygen gas flow rate was between 0.1 L/min and 0.5 L/min, whereas the Ar gas flow rate was set at 10 L/min. The surface was investigated by contact angle meter and X-ray photoelectron spectroscopy (XPS) to determine the differences between untreated and treated surfaces. The results indicated that the low-pressure high-frequency plasma chemical vapor deposition system could be used for surface modification.