The surface characteristics of the carbon nanotube thin films (CNTFs) electrodes have been treated with the oxygen plasma to successfully demonstrate, the greater specific capacitance of the supercapacitors. With the treatment time of 60 s, the specific capacitance could raise from 23.7 to 49.3 F g−1 with respect to the as-sprayed CNTFs under the cyclic voltammetry measurement. The improvement ratio in specific capacitance of plasma-treated supercapacitor as compare to none-treated supercapacitor was 2.1 times under condition of 1 M Na2SO4 solution at a scan rate of 100 mV s−1. The capacitance retention remain about 96.5% after 5000 cycles at current density of 1 A g−1. Hence, this study exhibited that the modified CNTFs as the electrodes of supercapacitors are promising in the future developments for the energy-storage devices.