Abstract: Based on coal mining layout features and technical conditions of production in Haoda Mine, the paper researches the seam spontaneous combustion prevention applicability of nitrogen injection technology by open bypass in mining process, on the basic of optimizing relevant parameters such as nitrogen injection amount and pipe diameter, nitrogen injection technology by open bypass have been successfully used in spontaneous combustion prevention of IV-2 seam. Practice shows that in the implementation of nitrogen injection technology by open bypass, through the beam pipe monitoring, CO gas concentration is below 14×10^-6, no other heavy hydrocarbon gas has been detected, float coal oxidation has been greatly curbed.