Abstract: Rockfill material, as the primary construction material for earth-rock dams, exhibits dynamic deformation characteristics under seismic action that are influenced by particle shape, gradation, and relative density. Current research on the effect of particle shape on the mechanical properties of rockfill mainly focuses on static characteristics, with relatively limited studies on dynamic properties. Artificially simulated rockfill materials of various shapes were prepared using a cement paste casting method, followed by cyclic triaxial tests. The study investigated the effect of particle shape on dynamic residual strain and particle breakage. The results indicate that the artificially simulated rockfill material prepared by this method can approximate the dynamic deformation characteristics of natural rockfill. Under low confining pressure, residual volumetric strain decreases as the shape coefficient increases, whereas under high confining pressure, the opposite trend is observed. Axial residual strain first increases and then decreases with an increase in shape coefficient. Under identical stress conditions, a smaller shape coefficient corresponds to a lower particle breakage rate. Additionally, the study established a relationship between particle breakage rate, shape coefficient, and confining pressure.