Earthquake-induced slope stability has been evaluated by the force-equilibrium of soil mass in normal engineering practice. But this method can't evaluate how large the deformation will develop and how far the effect reaches down-slope in flow-type failures. This study aims the development of evaluation method for flow displacements of slopes during earthquake in terms of energy. An innovative model test is developed, in which the energy dissipated in slope failure is measured on a shake table. Based on the theoretical considerations on the simplified block model and the model tests, a framework of performance based design for slopes against earthquakes has been proposed.