In this study, we made low temperature plasma reactor in order to treat safely NOx which included in the gas. We investigated experimently and inspected efficiency characteristics of equipment about flow rate of reactant material and discharge input power which supplied into reactor. As a reaction gas, by using mixture gas of NO/N2 and N2/O2, we setted up initial NO concentration and supplied the speed of a current to 1~4 l/min. When the amount of flow increased, reduction rate of NO was low. Also when discharge input power was high, decomposition of NO was easy. Also the longer delay time of reaction material and the higher discharge input power was, the higher decomposition energy efficiency was. And when the amount of flow was much, and the more discharge input power increased, the more ozone generated.