Abstract: In view of the situation that CO concentration in the upper corner of 2301 working surface of mine fluctuates greatly, which affects the safe ventilation of the mine, the CO source is comprehensively determined through field investigation, laboratory test and field test, and the following conclusions are determined: The CO in the upper part mainly comes from the low temperature oxidation of coal.The test confirms that the CO gas concentration is positively correlated with the temperature during the oxidation process of the coal sample from 40.0 ℃ to 285.0 ℃.At multiple temperature stages, such as 40.0～100 ℃,100.0 ～150.0 ℃,150.0～260 ℃ and above 260.0 ℃,the CO gas concentration is positively correlated with the temperature.The CO production increased step by step, and through the measurement of the three zones of coal spontaneous ignition in the goaf, it was determined that with the reduction of the deep air leakage in the goaf and the increase of the oxidation time of the left coal in the goaf, the deep oxygen consumption in the goaf increased, the air leakage decreased, and the oxygen concentration gradually decreased.According to the current situation of CO,a variety of treatment measures including dry ice fire prevention are put forward.Field practice shows that CO treatment measures are effective.