Abstract: With large-scale exploration of underground resources，stability of large-scale deep-buried stopes with hard rocks attracts more and more attention.Combined with the feasibility study on mining，and based on the primary-stage basic geological exploration，the stress of original rock in mining area and its physical and mechanical properties are achieved.On this basis，FLAC software is adopted to make the numerical simulation on stability of mined-out area（group).5 typical indexes are chosen to consider the excavation of underground mined-out area，including maximum tensile stress，maximum compressive stress，plastic zone area，tensile failure area and displacement of key position.With the orthogonal experiment design，the effect of stope structural parameters on the stope stability under different evaluation index is analyzed to obtain the optimal stope structural parameters.Through comprehensive analysis，the stope structural parameters for design reference are achieved.

Key words: Mined-out area(group), Stability, Plastic zone area, Orthogonal experiment design