Abstract: In view of the engineering practice in replacement and recycling of horizontal-boundary isolating pillar during the transition from open pit to underground，the finite element analysis software GeoFBA is used to establish the numerical calculation model to evaluate the feasibility and risk of the key techniques for replacement and recycling of horizontal boundary isolating pillars with the artificial filling bodyThe stress distribution laws and displacement trends on the underground environment before or after the replacement of horizontal boundary isolating pillars are revealed，and the optimal artificial replacement and recycling sequences are determinedThe simulation results provide an important guiding for the safety replacement and recycling of the horizontal-boundary isolating pillars in the mine.

Key words: Transition from open pit to underground, Horizontal boundary isolating pillars, Replacement, Recycling