Abstract: The evaluation of stability of surrounding rock is a complicated uncertainty system problem.Based on the set pair analysis(SPA) and the variable fuzzy sets theory,a new fuzzy comprehensive classification model was established.In order to simplify the evaluation procedure and improve the accuracy and reliability of results,a new method to construct relative difference degree was proposed.Moreover,it was shown by comparison of results between a practical example and other methods that the proposed method used to evaluate the stability of surrounding rock was feasible and effective,and more objective.