Abstract: In order to deeply study the source law of high volume fraction CO in the two-lane broken rock zone of working face, scientifically formulate preventive measures to prevent fire in the two lanes, and investigate the CO change in the overlying goaf, the adjacent goaf and the working face with the mining. The results show that: with the working face mining, no high volume fraction CO was not found in the overlying goaf and adjacent goaf, while high volume fraction CO were found in the observation boreholes of this layer, which proved that the two roadways did not adopt full-face spraying during the mining process; under the condition of in-situ stress, the low temperature oxidation time of cracked coal in the broken rock zone is long, and the broken coal is caused by low temperature oxidation, and natural oxidation reaction is more likely to occur in the loosening circle of transport roadway than in the loosening circle of return air roadway.