Nonthermal plasma (NTP) used for NO removal has been studied for a long time, but how to achieve the desired product with lower energy consumption is still a barrier for its industrial application. Dielectric barrier discharge (DBD) energized via an AC power supply was used to generate NTP. Energy cost (EC, MJ/mol) and product measurements were performed to reveal the effect of O-2 content, NO concentration, flow rate, and specific energy density (SED, J/L) on the performance of DBD. The products (NO, NO2, N2O, and O-3) of different SEDs were experimentally measured at 303 +/- 2 K. On the basis of the variation of products with the change in SED, the possible dominant plasma reaction and corresponding species were discussed. The dominant reaction of DBD processes can be categorized into oxidation, reduction, and product reactions with increasing SED from 400 to 3500 J/L. Lower SED and higher O-2 content are beneficial for the conversion of NO to NO2 and O-2 to O-3. The O atoms and temperature play a significant role in the interconversion of NO and NO2. A limitless increase in SED will reduce the conversion of both NO to NO2 and NO to N-2 due to the product's reaction with O and N atoms, respectively. The N2O was observed in all DBD systems with the feeding of N-2/O-2.