<p>Coseismic landslides are one of the most catastrophic secondary geological hazards induced by earthquakes, which can cause significant causalities and infrastructure damages on their runout paths. Due to its strong capability in dealing with large-deformation geotechnical problems, the material point method (MPM) has been increasingly adopted to investigate the dynamic process of earthquake-triggered landslides. In this paper, a simple MPM framework for analysing seismic behaviours of rock slopes with pre-existing slip surfaces is introduced. The framework is firstly validated by simulating the sliding process of a single block under cycle loading, and then applied to reproduce the dynamic failure and runout process of the Daguangbao landslide triggered by the Wenchuan earthquake. It was shown that the whole dynamic stages of the Daguangbao landslide, including the seismic slope failure, the landslide runout and the final deposition, can be reproduced satisfyingly in a unified three-dimensional way, by applying a state-dependent frictional weakening contact law for the joint interface and a strain-softening Mohr–Coulomb model for the rock mass, with all the model parameters obtained experimentally.</p>