In order to reduce the impact of ventilation air methane (VAM) emission on the greenhouse effect, we investigated the oxidation pattern of VAM with a concentration of 0.75% and its mixing method with lignite and anthracite, and the effect of the calcareous mudstone dust in VAM on the VAM in mixed firing system. Calcareous mudstone dust with different metal oxide content was mixed with different coal species and placed in this gas environment by using a tube furnace system to simulate a premixed gas environment of VAM and air. X-ray diffraction (XRD) analysis was used to analyze, the mixed firing products. The study shows that: calcareous mudstone dust can promote the oxidation of gas, and the oxidation efficiency increases with the increase of metal oxide content. Calcareous mudstone dust can promote the oxidation of VAM in the mixed firing system at the same temperature, and the higher the metal oxide content of calcareous mudstone dust, the lower the temperature at which the conversion of spent air gas reaches its limit. According to the effect of dust on the gas conversion of the two coal blending systems, it can be seen that although the gas conversion rate of the lignite system is always higher than that of the anthracite system, the dust has a negative effect on the conversion of the VAM in the lignite system and a positive effect on the anthracite system, so the effect of dust on the anthracite blending system is better than that on the lignite system. Calcareous mudstone dust also plays the role of sulfur fixation, so the calcareous mudstone dust involved in the process of discharging VAM from the mine can be left untreated and passed into the coal-fired boiler together with VAM.