Abstract：It is a controversial problem to assess comprehensively the global stability of high-steep rock slope of the Three Gorges Project permanent shiplock. The information on slope stability includes geological data，results of numerical analysis，measuremental data，experiential knowledge，and so on. Therefore，a suitable analytical methodology of system engineering integrating the comprehensive qualitative and quantitative information is needed. A multi-index system and model，which is able to evaluate comprehensively the global stability of high-steep rock slope by using extension theory，is proposed. The qualitative grade and quantitative degree for the global stability of high-steep rock slope by the index system and model can be obtained. The slope stability can be assessed dynamically. Analytic Hierarchy Process method has been used to compute the subjective weights of evaluation indexes. The objective weights can be obtained by calculating the relational degree between evaluation indexes and grades with extension theory. By combination of the views of both the subjective and objective weights，an optimization theory has been used to calculate the weights for index evaluation. The results have shown that for the high-steep rock slope of the Three Gorges Project permanent shiplock，its grade and degree of global stability are 1 and 1.86，respectively. Then the global stability can be ranged between excellent and good. The numerical example has shown that the proposed method is feasible and effective，and the evaluation results are reasonable. In addition，this method can also be used to assess dam health，rock quality，and dam aging.
