This paper first establish the index system of enterprise alliance stability evaluation, which composed of 3 ranks, 2 modules, 9 factors and 24 indexes; then we use the method AHP to determine the weight of each index in every rank. Finally, we appraise the alliance stability of one steel & iron enterprise and logistics enterprise using the scores given by experts. Furthermore, we draw the conclusion that the enterprise alliance is slightly stable, and put forward rational suggestions to enforce the enterprise alliance stability