Utilization of landfill gas is mainly to power generation through burning in internal combustion engine, in which the 1 MW scaled engines are dominantly used. In order to investigate the NOxemissions condition of landfill gas engine, two types of engines form different manufacturers were tested under normal working operation. Results showed that NOxconcentration in gas flue was quite high, and it was reducing with the increased of power load. The NO2 consists evidently percentage of NOx,and the ratio of NO2/NO increased with increasing power load. As all the measured NOxconcentrations in emission flue were higher than the required limitation i.e. 500mg/m3,the work of flue gas denitrification for landfill gas engine becomes quite necessary.