Abstract: To further definite the generation mechanism and routes of CO in coal oxidation,infrared spectrometer and in-situ reaction pool were used to investigate the change rule of aldehyde group,ketone group and quinone group with changing temperatures and CO concentrations,meanwhile,the apparent activation energy of CO precursor was calculat- ed. The results show that CO is generated by different precursors. The apparent activation energy in generating three kinds of precursors is less than the activation energy in releasing CO,so the reactive rate for the production of CO pre- cursors is greater than the reactive rate for the decomposition of CO precursors. In the coal initial phase at low temper- ature,ketone compounds are main precursor to generate CO in lignite,while quinones compounds serve as the main precursor to generate CO in anthracite. When oxidizing temperature is up to 80 ℃ ,three kinds of functional groups of compound are CO precursor. When temperature is higher than 150 ℃ ,aldehyde group is the precursor of CO,regard- less of coal type.