Abstract: coal seam spontaneous combustion is one of the grave hidden perils to coal mine safety production,how to govern coal spontaneous combustion has become the key projects of the mine safety production engineering.Based on the application practice of expansion filling fire sealing wall's construct technology used on inclined wind well's fire prevention in Dongpo mine,this paper expounds the expansion filling material's composition and performance,filling and constructed technology,the expansion filling airtight wall's underground construct test and it's technical and economical benefit.Application practice shows that initial setting time of the expansion filling material is about 20～30 minutes,its compressive strength achieves to 3.3MPa,and the coefficient of expansion is approximately 20%.The filling fire sealing wall airtight performance good,there is no air leakage,string wind phenomenon after its filling and the expected results have been achieved.