Abstract: Opposing mining and breakthrough between adjacent longwall faces can induce complex stress superposition and intensify strata behavior, posing a significant threat to mine safety. Taking the 30512 longwall face in Tashan Coal Mine and the 8207 longwall face in an adjacent mine as the engineering background, theoretical analysis was used to investigate the stress state of the mine-boundary protective coal pillar at different mining stages of the two faces, while numerical simulation was conducted to analyze the stress and plastic-zone distribution of the protective coal pillar at different distances between the two advancing faces. The results show that the coal pillar between the two longwall faces experiences four stages of stress evolution. During opposing mining and breakthrough, the pillar is subjected to the superposition of stress increments induced by roadway excavation and advance abutment pressures generated by the two longwall faces. The highest stress concentration occurs in the coal pillar when the adjacent faces approach breakthrough, with a maximum stress of 26.6 MPa and a stress concentration factor of 3.04. Under single-side goaf conditions, the lateral abutment pressure affects a range of 34 m within the mine-boundary coal pillar, which is greater than half of the pillar width. Based on the mechanism of strong strata behavior, comprehensive prevention and control measures were developed, and field monitoring of strata behavior verified their effectiveness.