Abstract: In order to solve the problem of spontaneous combustion of residual coal in goaf in 8059 working face of Yaoqiao Coal Mine, a geometric model of the goaf seepage field was established.By means of numerical simulation, the distribution of O₂ volume fraction in goaf was studied under different injection positions and injection flows of CO₂.The results show that when CO₂ is not injected, the maximum oxidation zone width in goaf is about 60 m; after CO₂ injection, the maximum oxidation zone width is reduced to about 20 m, the oxidation zone width decreases with the increase of CO₂ injection, the O₂ volume fraction in goaf decreases significantly, especially in the air inlet side; the best CO₂ injection port is located at one side of the air inlet roadway about 40 m away from the working face, when the injection volume is 540 m³/h to 720 m³/h, it is relatively suitable. Through the on-site pressure injection of CO₂ in goaf for fire prevention, the hidden danger of spontaneous combustion in goaf is effectively eliminated, and the safe production of the working face is guaranteed.