To prevent and control rockburst disasters induced by the fracture of thick-hard key strata, the energy release mechanism was revealed based on the key stratum theory. Analysis indicates that the bending elastic energy released during key stratum fracture is proportional to the square of the rock stratum thickness and the 2.5th power of the tensile strength. Furthermore, the residual energy propagating to the roadways determines the rockburst risk. A technique utilizing overburden bed separation grouting to control the key stratum was proposed. By filling the mining-induced separation spaces, a compacted load-bearing zone is formed in the central goaf, reshaping the overburden stress field to inhibit key stratum fracture. Numerical simulation studies demonstrated that after grouting, the coal stress concentration coefficient decreased by an average of 10%, while the peak stress in the central goaf increased by 149%. Engineering practice showed that following grout filling, the proportion of high-energy microseismic events (≥103J) at the working face decreased from 16.98% to 3.72%, significantly reducing the rockburst risk.