Abstract: Safety thickness of roof is the corresponding thickness when the roof reach the critical failure state. Simulation analysis was done on shore which setting different thickness of blind ore body exploitation of bottom Yeshan iron ore by dichotomy optimization theory, much accurate safety thickness of roof was obtained, and it furthest recovered the mineral resources and assure the safety stoping of orebody at the same time.

Key words: Safety thickness of roof, Critical failure state, Dichotomy optimization