Abstract: The rock materials taken from Jilintai rockfill dam are tested in the large diameter triaxial cell. In this paper the test results are introduced, however, the major attention is focused on the residual deformation of materials under cyclic loading. It is concluded that the rock materials contract considerably under cyclic loading, and this is particularly true for high confining pressure. Therefore, if this behavior is neglected in the analysis of permanent deformation of high rockfill dams, inadmissible error will result.