Abstract: The paper sets up an installation to produce glow discharge plasma and treat the capacitor film. Three kinds of capacitor films, including PP, PET and PPS films are treated by N2, O2 and Ar plasma. The infrared spectrums show that the change of matter on the film surface is affected by the kind of film, plasma and the treatment strength. The SEM images show apparent corrosions on the treated film surface, which can be explained as that the amorphous component is etched off, and the crystal grains are exposed. Energy spectrum analysis indicates that element of C decreases a little, while N and O increase slightly. The DC Breakdown voltages of treated and untreated films are nearly the same. However, the corrosion of the film surface due to the plasma treatment will make the immersion of fil