The preparation of SiO-x coating as barrier layer deposited on PET surface by magnetized plasma enhanced chemical vapor deposition (MPECVD) through the roll-to-roll process was introduced. The factors influencing barrier performance and color change of the film under different technological conditions were studied. The result showed that PET coated with SiO-x is more transparent in high oxygen concentration, and the SiO-x coatings are near colorless. The composition and structure of the coatings were analyzed by Fourier transform infrared (FTIR), and the color degree and light transmittance were analyzed by spectrophotometer and UV-Visible spectroscopy respectively. The mechanism of the influences was analyzed.