Abstract: Using tracer detection technology and computational fluid dynamics numerical simulation method, the air leakage law in E2307 working face of Y-type ventilation in goaf of Gaohe Coal Mine was studied in this paper. The arrangement of release point and sampling point of SF₆ gas was introduced, the tracer detection scheme was developed, and the detection data was analyzed and calculated.The results show that the air leakage rate in working face in goaf is 16.43%; there are several air leakage passages in goaf, and the air leakage speed in goaf ranges from 0.05 m/s to 0.14 m/s. Combined with the detection results of tracer gas leakage, a numerical simulation model is established, the simulation results show that the air leakage rate in goaf is 13.35%, which is close to the field measurement results; the air leakage path in goaf is fan-shaped, which is deflected from the working face to gob-side entry retaining; the oxygen content in goaf is positively correlated with the distance from working face and gob-side entry retaining, the distribution of scattered tropics, oxidation zone and asphyxiation zone in goaf is L-type, the range of this "three zones" change with the increase of height, and the scattered tropics gradually disappear when the height is greater than 26.2 m.