Abstract: The stability of boundary pillar can be found across in open pit and underground mine shifting. In this paper, based on the conditions of Dabaoshan Mine which is a open pit and underground mine, the stabilities of boundary pillar are calculated and analysed by using the method of numerical simulation. It is found that the tensile stress of the roof of mine-out areas is the main factor of the stabilities of boundary pillar. The boundary pillar’s safety thickness is calculated by the method of numerical simulation and have compared and analysed with other results which are calculated by five representative ways. Through summing up the calculation results by summation normalization method and approximating the result by polynomial numerical approximation method, the relationship between the span of mine-out areas and the boundary pillar’s safety thickness has been established. It can be used to prove , supplement for the stability of boundary pillar of open pit and underground mine and can guide the design of the boundary pillar’s safety thickness. This will be of great significances to instruct the safety production of open pit and underground mine.

Key words: open pit and underground mine；boundary pillar&rsquo, s safety thickness；numerical analysis；stability