In view of the problem that the carbon monoxide gas emitted from the coal mining face during the mining period affects the normal production of the working face, coal samples were collected in three mines to analyze the source of carbon monoxide gas. The coal sample crushing test was carried out under two different gas environments, and the variation law of coal sample temperature and carbon monoxide gas was analyzed. With the help of constant temperature heating test, the changes of two kinds of gas concentration in coal samples under different conditions of temperature and test environment were analyzed. The results show that the concentration of carbon monoxide gas is smaller than 3.0×10-5 when the coal sample is crushed under nitrogen condition. The reason for the gas generation is that the coal is crushed mechanically and the decarbonylation is activated. The concentration of carbon monoxide gas formed in the crushing process of coal under air conditions is smaller than 6.0×10-3, and the carbon monoxide gas comes from the coal-oxygen composite reaction. The heating rates of coal samples under air and nitrogen conditions are 1.0 ℃/s and 0.6 ℃/s, respectively. In the nitrogen environment, the three coal samples did not produce carbon monoxide gas, but a part of the adsorbed methane gas in the coal sample itself was resolved due to the high temperature effect, indicating that there was no adsorbed carbon monoxide gas in the coal body. When the temperature of coal body exceeds 80 ℃, the oxidation reaction of coal sample is intensified, and the concentration of carbon monoxide increases exponentially.