© 2019 The Institute of Electrical Engineers of Japan. The environmental improvements by pulsed discharge plasma, a type of non-thermal plasma, have received much attention all over the world. The observation of discharge plasmas is beneficial for better understanding of the plasma physics of this growing field. Recently, nanosecond (ns) pulsed discharge with a short pulse duration of 5 ns achieved the higher energy efficiency on ozone generation and NO removal. However, the underlying mechanisms of these high efficiencies remain unclear. In the present study, the effects of electrode geometry on propagation process of ns pulsed discharge in coaxial electrodes were investigated using an ICCD camera. As the results, increasing wire diameters from 0.2 mm to 2.0 mm lead the different streamer discharge parameters; propagation velocity of streamer heads from 4.8 mm/ns to 12.5 mm/ns, peak of discharge current from 243 A to 328 A, respectively. Therefore, it is concluded that the wire diameter is one of the paramount parameters to control the characteristics of the ns pulsed streamer discharge.