The pilot-scale NO_x removal from boiler emission of city gas and heavy oil fuels was performed using indirect plasma and a chemical hybrid process. The flue gas flow rate was in the range of 455〜1,440 Nm^3/h, and NO_x concentration of 40 ppm in city gas firing and 96 ppm in heavy oil firing. The relation between NO_x removal efficiency and packing material height was investigated in order to reduce Na_2SO_3 consumption rate, varying the height from 2.1 m to 0 m. The packing height was 0.75 m enough to achieve 70% of NO_x removal efficiency for city gas, and 60% of NO_x removal efficiency for heavy oil.