[Objective] To analyze the influence factors of the Mengdigou reservoir bank stability in order to provide new train of thought to evaluate the stability of reservoir bank.[Methods] On the basis of the analysis of the engineering geological conditions and the interpretation of unfavorable geological phenomenon, this paper classified the bank into different segments. Then using the principle of the slope unit, we then taken these segments as independent research objects and analyzed the factors affecting the bank stability. And then we used three-dimension factor safety of slope units as an index of the stability evaluation and used analytic hierarchy process(AHP) to analyze the factors affecting slope stability. Finally we established hierarchy analysis and evaluation methods for the stability of reservoir bank based on the slope unit.[Results] The method was tested in the engineering practice, showing that the method is reliable and practical.[Conclusion] Tanking the slope unit as the research object, using the AHP can effectively analyze the stability of reservoir bank, which can support the decision of project.