Abstract: Based on the Tatsuoka's cumulative damage theory of soil strains under irregular loadings, a numerical analysis method for the earthquake-induced permanent deformation of rockfill dams is proposed. The mechanical experiments of the rockfill materials are carried out by use of the large static and dynamic triaxial apparatus, and the material parameters related to the stress-strain relationship and cumulative strain model are determined. By use of the proposed method, the earthquake-induced permanent deformation characteristics of the rockfill dam under construction and after completion are studied respectively for the Iwate-Miyagi Nairiku earthquake of M7.2 on 14 June 2008 in Japan. The results show that the earthquake-induced settlement computed by the proposed method is basically consistent with the measured one under the construction of the dam. Moreover, the predicted value of the earthquake-induced settlement at the crest after the completion of the dam is within the reasonable range by comparison of the measured data of the other similar dams.