This entry reviews new achievements and the status of the nonthermal plasma (NTP) catalytic process for nitrogen oxides (NOx) removal. The combination of NTP with heterogeneous catalysts has been extensively reported. Therefore, the combination modes including plasma-enhanced catalysis, plasma-driven catalysis, plasma-assisted NOx storage, and decomposition process are outlined in this entry. Compared with plasma alone and selective catalytic reduction (SCR) alone, the synergistic function between NTP and heterogeneous catalysts has been considered as the primary factor for the improvement of NOx removal. Particular attention is paid to the plasma catalytic process of NOx decomposition, hydrocarbon-SCR and ammonia-SCR. An overview is given for the understanding of the mechanisms in each plasma catalytic process.