The PANI-CNTs composite material was synthesized through emulsion polymerization, and then the composite had been modified by the oxygen plasma to get the electrode material for super-capacitor. The influences of the modification time on the electrode material surface property and the electrochemical performance were investigated. And based on the analysis of the scanning electron microscope(SEM) and fourier transform-infrared spectroscopy (FT-IR), the results revealed that the particle size of the composite material become smaller, more micro pores were etched by the oxygen plasma and some active functional groups were introduced. The electrochemical tests demonstrated that the PANI/CNTs composite material modified by the oxygen material after 10 min has perfect capacitive properties, the specific capacitance is 287.8 Fg-1, and the ESR is 0.320 Ω.