Abstract: Selective catalytic reduction (SCR) activity for NOx conversion to N2 over 7% MoO3/γAl2O3 (mass fraction) was investigated with Dimethylether (DME) as a reductant. The effects of the reaction temperature, DME/NO ratio as well as the oxygen inlet concentration were studied respectively. The carboncontaining product distributions were presented. NOx conversion with NO and NO2 respectively as NOx source was also investigated. The results show that between the range of 250℃ to 500℃, under atmospheric pressure, when operation temperature increases, NOx conversion increases at the beginning and then decreases. DME/NO ratio has a little impact on NO conversion. When the oxygen inlet concentration increases, NOx conversion increases at the beginning and then decreases, and the highest conversion rate of NO is about 53% when the oxygen inlet concentration is 5%. NO2 is easier for selective reduction than NO with DME as the reductant. The main carboncontaining products are CO and CO2, while a little CH3OH and H2CO have also been detected during the experiment.