Abstract: In order to improve the fire-fighting effect of fire-fighting materials, the defects of poor coverage and low viscosity of some commonly used fire-fighting materials were optimized. In this paper, the temperature sensitive composite gel was prepared with methyl cellulose, potassium persulfate and N,N'-methylene bisacrylamide as raw materials. A large-scale simulation fire extinguishing experimental platform was designed in a coal mine to study the cooling rate and flame retardancy of the temperature sensitive composite gel. It is found that the optimal injection amount of thermosensitive composite gel is 20% of the coal mass, and it has excellent fire extinguishing performance at different temperatures, but at the coal temperature of 600 ℃, the fire extinguishing effect of thermosensitive composite gel is better, and the coal temperature can be reduced to 50 ℃ in 8 seconds, and the CO concentration can be reduced to 30 ×10^-6. The temperature-sensitive composite gel can seal the coal fissure and wrap the coal completely, forming a gel film on its surface to prevent the coal-oxygen composite reaction, so as to achieve the purpose of rapid fire extinguishing.