The instability type of rock burst in the multi key layer coal pillar system of the deep fully mechanized mining face is a common type of rock burst in the deep mining area of Ordos. Currently, there is no unified and mature treatment plan on site, and the occurrence of rock burst still occurs from time to time. This article takes the 3102 working face of a Coal Mine in the deep mining area of Ordos as the engineering background, and adopts methods such as theoretical analysis, numerical simulation, and on-site measurement, A study was conducted on the instability induced impact mechanism of the multi key layer coal pillar system in deep fully mechanized mining faces, and the following conclusions were drawn: the spatial structural evolution law of the deep multi key layer coal pillar system was explored, the loading mode of the section coal pillar bearing multi key layers was studied, the deformation and stress transformation function relationship of the multi key layer wide coal pillar system was analyzed, and the engineering criterion for instability induced impact of the multi key layer wide coal pillar system was derived. Revealed the instability induced impact mechanism of the deep multi key layer coal pillar system: when the goaf on both sides of the coal pillar is mined out, the low level "ILZ" and in-plane "DLZ" break the key rock group and load it to the wide coal pillar for compression deformation. Afterwards, the key rock group of the "DLZ" in the mining area flexes or even breaks, transferring stress to the loading section of the coal pillar. When its bearing stress exceeds the instability threshold, the overall instability impact occurs. Numerical simulation was conducted to study the changes in stress magnitude and distribution characteristics of coal pillars in different shrinkage width conditions in the mining area. As the width of the bearing coal pillars in the section increases, the stress distribution characteristics transition from a platform type to a saddle type, and the degree of stress concentration and overall impact risk level continue to decrease. Field measurements have verified the anti impact safety of the 120m section of coal pillars.