Abstract: The mined-out zone groups have become one of the most potential safety factors for mines.In view of the mined-out zone′s occurrence，the RG one-dimensional and two-dimensional models were established.Considering the effect of stress redistribution on the stability of the system，the complex problem of the mined-out zone group system instability was transformed to the comparison between the unit instability probability and the critical instability probability.The critical instability probability of the mined-out zone groups under one-dimensional and two-dimensional conditions are put forwards.Mined-out zone 1 and 2 in Qijiaojing Iron Mine were calculated and verified by this method，showing that the calculation results are consistent with the actual situation.It is indicated that the method has a certain practicality to evaluate stability of mined-out zone. RG method|Mined-out zone group|Critical probability|Evaluation