Abstract: In order to effectively analyze the gas components of the mixture produced by the underground coal gasification process, a three-dimensional （3D） mathematical model of the underground gasification process of the fixed bed coal is established using the computational fluid dynamics theory under the uniform distribution of a given geometric structure and coal block. The reactor in this model considers gas-solid two-phase flow and generates a discrete numerical grid. The gas-phase k-ε turbulence model was used to analyze the technical parameters of the model using ANSYS/Fluent software. The gas components （CH₄, CO₂, CO and H₂） in the coal gasification process were analyzed qualitatively and quantitatively. The results show that the calculated values of the components obtained from the numerical model agree well with the measured values, and the average relative error is 12.17%. In addition, the applicability of the proposed numerical model is verified based on the obtained correlation coefficient.