The nonlinear effect of perimeter joint on the performance of Xiao Wan high arch dam (292.0m high) is studied with nonlinear FEM in this paper. Nonlinear relation between the stress and deformation on the surface of the joint is adopted, and coupling effect between material nonlinearity of the dam, foundation and contact nonlinerity of joint is considered, opening and slipping of the joint are modeled in the analysis. Variation of the stress and displacement at the key location of the arch dam with perimeter joint on different crack depth, different elevation and with or without water pressure on the crack face is compared. Crack and yield near dam heel with or without joint are studied, The result of analysis demonstrates that setting perimeter joint could reduce cantilever stress near the dam heel effectively, and the stress near dam heel with joint has a great improvement ,while little difference of stress and displacement occurs on the other location of the dam.