Research of the formation mechanism of spontaneous combustion sources in coal mines shows that the pillars in goaf are the major cause of accidents. For safe mining of coal seams, prone to spontaneous combustion, it is necessary to use the pillarless technology. For isolation of extraction area and safe ventilation of the longwall face’s part during the mining of the coal pillar on the same line with the working face it is necessary to form an artificial strip of non-combustible materials on the border of the excavation of the pillars. The research presents the results of studies of the stress-deformed state of the rocks, coal pillars and artificial strips at different stages of mining of the extraction area using the pillarless technology with artificial strips. The zones of the highest stresses and the reasons for their formation are determined. Recommendations for determining the parameters of artificial strips are given.