This work aimed at revealing the mechanism of strong strata behavior in extra-thick coal seam mining which was influenced by an overlying coal pillar (OCP). To this end, the evolution characteristics of the stress and displacement in advance coal body of the working face were studied via numerical simulation. On this basis, the mechanism of strong strata behavior in working face affected by OCP was revealed. In situ monitoring also demonstrated that, as the working face mining near to the position of OCP, severe rib spalling and roadway deformation frequently appeared. The scheme of strengthening the hydraulic supports resistance and adding anchor cables was put forward to control the surrounding rocks in the stope. As a result, the maximum deformation of the roadway height was 0.66m and could completely meet the demands for safe mining. The study on the mechanism of strong strata behavior in working face and the strengthen supporting scheme would provide a theoretical basis for similar mining conditions, thus ensure safe and efficiency coal seam mining.