Abstract: In order to explore the source of low metamorphic coal CO source and reduce the risk of natural fire in the coal seam, Taking the 3^# coal seam of Dananhu No.1 mine as the research object, the CO generation rule in the CO occurrence, mining and cutting of the 3^# coal seam and the CO source ratio in the corner of the return air are studied by means of temperature programming experiment, experiment simulation and field observation. The results show that when coal is pulverized without oxygen, a large number of functional groups and free radicals generated by the covalent bond fracture of coal molecules interact to produce a very small amount of CO. When coal is pulverized under oxygen, a large amount of CO is produced. With the increase of specific surface area of coal samples, the volume fraction of CO increases and eventually becomes stable. The coal cutting machine produces high temperature, which oxidizes the coal body and produces CO volume fraction of 30−50 ppm. The CO from the goaf accounts for 28% of the total integral number of the CO from the return air corner, and more than 70% of the CO comes from the oxidation of the crushed coal after the production period. According to the CO source of low metamorphic coal, comprehensive prevention and control measures such as spraying CO compound inhibitor after the frame, pressure injection of cold nitrogen in goaf and air leakage plugging have been taken to reduce CO volume fraction in return air corner and return air flow significantly.