Abstract: To optimize the control effect of nitrogen injection fire-fighting technology, the No.8401 working face in Madaotou Coal Industry Company of Datong Coal Mine Group is taken as the research object. The numerical simulation method is used to study the influence of ventilation and advancing degree of working face on the scope of spontaneous combustion oxidation zone in goaf under nitrogen injection and non-nitrogen injection. The results show that whether nitrogen injection or not, the larger the air volume in the working face is, the wider the oxidation temperature rise zone is, and the greater the spontaneous combustion risk of goaf is. From the view point of preventing the goaf from spontaneous combustion, the air volume of the working face should be reduced as much as possible, i.e. the reasonable ventilation technology should be adopted. The reasonable range of air supply in No.8401 fully mechanized caving face is 1 400~1 755 m3/min. At the same time, it is concluded that the nitrogen injection measures must be taken in No.8401 fully mechanized caving face, and the monthly advancing degree of the working face should be no less than 36 m. Under the above conditions, the application effect of nitrogen injection fire-fighting technology is the best.