The research aims to study the feasibility of forming diamond-like carbon (DLC) films deposited on the PET surface through microwave surface-wave PECVD technique with barrier layer. With C2H2 as monomer and Ar as discharge gas, the DLC film was deposited on the organic PET material surface through microwave surface-wave PECVD technique. The influences of process parameters such as microwave discharge power, working pressure and monomer to working gas ratio on the deposition rate and barrier performance of DLC film were studied. The chemical structures and properties of DLC films were characterized by Fourier transform infrared spectroscopy (FTIR), atom force microscope (AFM) and some conventional surface probes. The structure and composition of DLC films varied with different process parameters of plasma discharge. The OTR and WVTR of the coated PET film can be reduced to 0.58 mL/(m2∙d) and 2.5 g/(m2∙d), respectively. DLC film has good barrier property to both oxygen and steam oxygen and can be used in high barrier packaging of food and drug.