Abstract: In order to explore the oxidation distribution of goaf under different nitrogen injection parameters. We simulate the oxygen distribution of goaf by FLUENT 3D mathematical model, and compared the results with that of measured. We calculate the influence of nitrogen injection under different nitrogen injection volume, different injection depth and different injection height on oxygen distribution. The research results show that nitrogen injection can significantly change the oxygen concentration nearby the inlet side, and the effect is obvious with the increases of nitrogen injection quantity. The reasonable amount of nitrogen injection is 350 m³/h for 110204 face, and the best location is about 40 m far from the workface. The impact of nitrogen injection focused on the inlet side, the observed data of "three zone" with nitrogen injection is a reasonable reference; the change of the height has obvious influence on the distribution of oxygen, the higher position has less affected on the oxygen concentration in lower part of the float coal.