Abstract: Based on variable fuzzy sets theory, the comprehensive evaluation system model of the stability of surrounding rock of mined-out area was set up. The evaluation indexes that influence the stability of surrounding rock of mined -out area and the grade indices for appraisal of stability were primarily explored. The evaluation results of the stability calculation were compared and analyzed using a mined-out area as an instance. The results of the study show that under three kinds of weight vector, the eigenvector of the sample belongs to the third grade, meaning the stability of mined-out area is level 3(the stability is bad).