Abstract: According to the mass conservation and volume ratio, and the definition of carbon isotope, the method of identifying the source in the mining process is proposed, and the multi-source mixed gas source calculation model is built. The influence of mining factors, natural factors and geological conditions on the source ratio is analyzed by analyzing the contribution ratio of gas in 11-2 and 13-1 coal seams. After sampling and analyzing the calculated results, it is found that the method can be successfully applied to the dynamic identification of the mixture gas source ratio of the ground extraction drilling, the closed wall of the gob and the back air of the bottom lane, and can accurately reflect the dynamic change of the proportion of the mixed gas sources in various locations, and the error can be controlled within 0.5 per thousand. It is also found that the proportion of the mixture of gas sources is mainly influenced by the geographical environment of the sampling point, the mining level of the working face, the location of the coal seam in the coal seam and the gob.