The overall stability of the high arch dam is one of the key issues in the construction of a hydropower project.Physical simulation and numerical calculation are the main methods to study this issue.Jinping I high arch dam is featured with complicated geologic structures of various types of faults,dykes, joints and fissures, and its overall stability is greatly influenced by these structures.It has great dam height, huge capacity of the reservoir and complicated reinforcement measures, so the safety and stability problem of the project is very prominent.In this paper, firstly, the evaluation basis for the safety factor of dam stability is established based on the comprehensive method.Than the methods of 3D geomechanical model test and 3D nonlinear FEM calculation are adopted to study the overall stability of Jinping I high arch dam under the condition of reinforced foundation.The working performance of the arch dam under normal conditions, and the deformation characteristics, failure patterns and mechanisms of the dam abutment and foundation under loading process are obtained by comprehensive analysis the results of the two methods.The analysis shows that the overall stability of safety coefficient is 5.2 ~ 6.0 by comprehensive model test and 5.98 by comprehensive FEM computation.The overall stability of Jinping I high arch dam is evaluated synthetically by combining the results of the two methods.The research results provide an important scientific basis for monitoring and safe operation of the project.They also can provide a reference for the stability analysis of other high arch dams.