Abstract: In order to explore the evolution laws of fissure field in fully mechanized top coal caving face in deep strata with strong rock burst. Taking the geological condition of 3 lower coal seam in Tengdong Coal Mine as an example, the meso parameters were established by empirical formula method, and the particle flow model of coal seam was established by PFC^3D software. The simulation studies on the change laws of porosity and the development of coal pillar fissures in fully mechanized top coal caving mining area were realized. The results show that the mining operation of the working face affects the change of porosity in the coal seam and the rock layer. When the working face is advanced to 15 m, the local porosity of the coal seam and rock formation increases. When the recovery distance reaches to 90 m, the porosity of coal seam in front of the working face is still up to 0.98, and the fractures of the overlying rock formation develop continuously. During the mining of the two working faces, the coal pillar fissures grow at different speeds and will eventually reach to a maximum value.