Abstract: Based on physical model tests of a classical concrete gravity dam, a macro-meso structure finite element model of dam bodies was developed that takes the concrete in the region of crack propagation as inhomogeneous materials at meso level and adopts an extended finite element method to simulate the whole propagation process in the dam. Crack propagation trajectories and curves of external load versus crack mouth opening displacement (P-CMOD) were obtained; the impacts of aggregate distribution and its volume content on the trajectories were studied. The results show that the calculated P-CMOD curves agree well with previous experiments. Aggregate distribution has a significant effect on the descending portion of the curves, while little effect on peak load and the trajectories. Differences in the trajectories are small when aggregate volume content varies from 60% to 80%.