The dynamic fracture behavior of mass concrete is crucial to the safety evaluation of concrete dams subjected to strong earthquake. Cylindrical specimens with a ring of preset crack were cast and direct tension tests were performed. Two loading rates were considered, i.e., 10 ^-6/s for quasi-static loading and 10 ^-3/s for dynamic loading. When calculating the fracture toughness, the influence of eccentricity in the tests was compensated. Next, the crack propagation process of mass concrete was modeled using the extended finite element method. From the test results it’s found that under quasi-static loading, the crack generally propagates along the interface between the aggregates and the matrix, while under dynamic loading, more aggregates are fractured. As compared to the case of quasi-static loading, the energy absorption capacity, fracture energy and fracture toughness increase for dynamic loading while the characteristic length decreases. Moreover, the numerically predicted P- CMOD curves agree well with the experimental measurements.