The effects of discharge polarity, discharge electrode configuration, and O2/CO2 ratio on NO oxidation by nonthermal plasma (NTP) and NOx removal by the combination of NTP and alkaline absorption in simulated flue gas were investigated in a combined system of a wire-cylinder plasma reactor and a bubble absorber. The preoxidation of NO by dc corona discharge is effective in promoting the NOx absorption. Both the NO oxidation efficiency and the NOx removal efficiency increase with the increase of applied voltage. The positive dc discharge exhibits much higher O3 formation and NO oxidation performances than the negative one. The increase of the discharge zone length and tooth slice number significantly influences the energy density in the plasma reactor and improves the NO oxidation efficiency for a fixed applied voltage. Increasing the O2/ CO2 ratio in the simulated flue gas obviously enhances the NO oxidation and NOx removal.