As to arch dam stress analysis, the conventional trial-load method has got lots of successful experience, but also has some disadvantages. For instance, it is hard to deal with complicated foundation, topography feature etc. At these aspects, the Finite Element Methods (FEM) has large advantage. In Xiluodu Arch Dam FEM analysis, the authors have adopt the program ANSYS 5.5.2, and completed Dam stress and deformation analysis; Dam overall stability analysis; Discharge orifice stress analysis; Foundation property sensitivity analysis; Foundation reinforcement analysis; Comparative analysis with Ertan Arch Dam etc. Aiming at evaluation of the computation results, the authors have conducted the mesh density sensitivity analysis and comparative analysis with ADAP program which specialized in arch dam analysis.