An upper bound limit analysis finite element method is developed to study the ultimate aseismic capacity of earth-rock dams. Considering the large value of the internal friction angle and the non-linear shear strength parameters of earth-rock materials, a static form, which is the corresponding dual problem of the second-order cone programming for upper bound limit analysis, is formulated with constraints based on the yield criterion, flow rule, boundary conditions, and the energy-work balance equation. The upper bound solution of ultimate aseismic capacity is then iteratively obtained by a state-of-the-art interior-point algorithm. The proposed method is applied to the seismic stability problem of a typical earth-rock dam. The results indicate that the earth-rock dams designed according to code have strong seismic capabilities, as the influence of vertical earthquake load is considered. These results also demonstrate the high calculation accuracy and practical value of the proposed method.