Desulfurization and Denitrification processes in two pulsed discharge plasma systems (NO/SO2/N2/O2/H2O and NO/SOSubscript text2/NSubscript text2/OSubscript text2) were simulated respectively, and then the removal characteristics of these two gas systems were analyzed. The results show that NO can be completely removed when the residence time is close to 1.3 s and SOSubscript text2 removal rate is 61.5% when the residence time reaches 3 s in a system containing water vapor (HSubscript text2O). When the system does not contain water vapor, NO removal rate is still much high, but SOSubscript text2 removal rate is approximately zero. When OSubscript text2 concentration is increased, NO removal velocity will be faster and the peak of the concentration curve of NOSubscript text2 will be higher. NO removing velocity is much faster in a system containing water vapor than that in a system without water vapor when both systems have almost the same OSubscript text2 concentration.