An experimental study on the effects of CO content on selective non-catalytic reduction（SNCR）of NOx was performed in a quartz tube reactor，using ammonia and urea solution as N-agent.The results showed that as the CO content increased：(1）Both the SNCR temperature window and the optimal DeNOx temperature shifted towards a lower temperature.Simultaneously，the temperature window was narrowed and the optimal DeNOx efficiency decreased，especially when using ammonia as reductant.(2）The peak of N2O emission became higher.When using urea solution as the reductant，N2O emission temperature window extended towards a lower temperature mainly.In the case of ammonia，N2O emission temperature window extended to both higher and lower temperatures.(3)The slip emission curves of both NH3 and HNCO shifted to a lower temperature.When setting φ（CO）/φ（urea）constant，the optimal DeNOx temperature dropped slightly with the increase of ratio of ammonia to nitrogen in the feed（β），and there was no change of the emission regime profiles about NOx，N2O，NH3 and HNCO as β or oxygen content changed.