Abstract: The application of rock-filled concrete (RFC) technology in high dams and large-scale projects is on the rise. Given the elevated seismic fortification intensity at some project sites is relatively high, there is a pressing need for enhanced structural design considerations for RFC dams, necessitating comprehensive research into the dynamic performance of RFC. This study employed a scaled-down testing approach to conduct a series of uniaxial and triaxial compression tests on RFC specimens subjected to varying confining pressures and strain rates. The results indicate that the uniaxial strength of RFC is positively correlated with the strain rate; however, it demonstrates a discernible decline as the size of coarse aggregates and the dimensions of the specimen increase. Confining pressure significantly enhances the dynamic strength of RFC. Under identical confining pressures, specimens containing larger aggregates demonstrate lower uniaxial strength but exhibit higher triaxial strength. This observation suggests that the mesoscopic characteristics of the self-sustaining framework formed by the coarse aggregates play a crucial role in influencing the strength of RFC. Based on the test results, a failure criterion is established within the octahedral stress space, thereby providing experimental evidence for the nonlinear analysis and seismic design of RFC structures.