Abstract: In order to solve the problem that common extinguishing agent and extinguishing method can't extinguish pulverized coal fire at depth level, an effective fire extinguishing agent was obtained by adding surfactant into water to reduce the surface tension and improve the wettability of coal powder. The extinguishing agent for pulverized coal fire at depth level was screen out by setting experimental device. The main formulations of fire extinguishing agent are 0.20% twain- 80, 0.10% ediaminetetraacetic acid tetrasodium, 0.05% diisooctyl succinate sodium sulfonate and 0.10% potassium carbonate solution. The penetration time of extinguishing agent to 0.25,0.50 and 0.75 m is obtained at the penetra⁃ tion pressure of 0.1,0.2 and 0.3 MPa respectively. Based on the experimental results,the formula for calculating the horizontal pene⁃ tration and spreading of pulverized coal for fire extinguishing agent is obtained.

Key words: the coal stack, extinguishing agent, pulverized coal deep-seated fire, the horizontal penetration