Abstract: By use of finite elements to model the dam body and of discontinuous contact elements to model the abutment, the abutment residual deformation and dam stress of Xiaowan arch dam under the design seismic load are calculated. The dynamic safety factor of the abutment rock is obtained with the critical condition of tensile stress reaching the tensile strength of the dam concrete. Calculation results show that the abutment of Xiaowan arch dam is safe.