Abstract: The coal of L5216 mechanized mining face in Lingxin Coal Mine is easy to appear spontaneous combustion. The working face interconnects with the upper multilayer gobs to form complex air leakage network. CO generated by high temperature oxidation of coal pillar, spreads to L5216 working face through cracks by the negative impact, which causes mined-out area severe fire situation and affects L5216 mechanized mining face production safety. Specific to the actual situation of L5216 mechanized mining face, the immediately ground drilling liquid nitrogen injection for fire extinguishing is employed. The ground drilling liquid nitrogen injection with multi-channel, big flow, direct injection for fire extinguishing eliminates the high temperature oxidation of gob effectively.