Abstract: In order to improve the inerting effect of the mine nitrogen injection technology, based on No.8202 fully-mechanized top coal caving mining face in Tasha n Mine as a background, the layout of the bean tube and temperature monitoring and measuring system was applied to continuously monitor and measure the CO、O2C oncentration and temperature of each measuring point in the goaf.The 02 concentration distribution contour map was drawn, the temperature rising rate was ftted and t he spontaneous combustion danger area was determined and divided.The results showed that the area with a distance of 30 ~ 170 m between the air intake side of the goaf and the coal mining face and the area with a distance of 30 ~ 220 m between the air retuning side and the coal mining face were the spontaneous combustion dan ger areas.With the comparisons, when the nitrogen injection flow was 2 500 m3/h, the location of the nitrogen injection hole (50 m, 100 m, 150 m and 200 m behind the coal mining face was affected to the inerting effect.In the low level top coal caving goaf, when the location of the nitrogen injection hole was 150 m behind the coal mini ng face, the spontaneous combustion danger area was reduced about 60 m.In the deep section of the goaf, the CO volume fraction was obviously reduced and was sta bilized about 19x 10-6.The inerting effect of the diluent oxygen was the best.