Abstract: Based on analyzing the characteristics and major affecting factors of stability of ore body at underhand cut-and-fill drift, and collecting a great deal of instances and expertise, a index evaluation system of stability of ore body was established. On this bases, a model to make an assessment of stability of ore body was established by using fuzzy approach. In the process, combining the trapezoidal distribution function and information distribution principle, a membership function of evaluation index was established, the weighing of evaluation index was defined by AHP, and the fuzzy proximity was calculated between the evaluation target fuzzy set and the standard set by hamming distance, . At last, the stability level of the object will be defined by the maximum membership principle. Few examples of a mental mine in Jiangxi was evaluated by using this model. Through field investigation and comparative analysis, the evaluation results are basically consistent with the actual situation. These application instances explain that the evaluation result is reasonable and credible.