The surface of poly(ethylene terephthalate) (PET) film was modified by low-temperature plasma with O-2, N-2, He, Ar, H-2, and CH4 gases, respectively. After being treated by low-temperature plasma, their surface wettability and chemical composition were investigated by means of electron spectroscopy for chemical analysis (ESCA) and contact angle measurement. The result shows that the surface wettability of PET can be improved by low-temperature plasma, and the effect of the modification is due mainly to the kind of the gases. Mainly because of the contribution of hydrogen bonding force y(S)degrees, the surface wettability of PET treated with O-2, N-2, He, and Ar plasma for a short time (3 min) increase sharply, and the surface wettability is also improved by H-2 plasma treatment; but the CH4 plasma treatment does not improve the wettability of PET. ESCA shows that the effect of wettability of PET is tightly related to the presence of polar functional groups that reside in the outermost surface layer of PET.