Abstract: As the most widely used construction material, concrete is common in military and civil transportation infrastructures. During its services life, concrete may bear dynamic loads such as high-speed penetration, blast and impact of vehicle, ship, rockfall and so on. On the mesoscale, concrete is three-phase material composed of mortar, coarse aggregates and interface transition zone (ITZ). The concrete 3D mesoscale model was established to analyze the crack generation and development, damage evolution, dynamic strength and its influencing factors of concrete. Firstly, randomly distributed convex polyhedron aggregates of random shapes and sizes were modeled based on the conventional “take-and-place” method, and improvement and control of volume fraction (up to 50%) were realized through aggregate drop simulation and reduction. Then, aggregates and mortar were meshed with tetrahedral elements to display their actual physical shapes. Besides, ITZ is represented by interface cohesive contact to improve computational efficiency. Furthermore, SHPB simulations of different coarse aggregates sizes are conducted and the accuracy of model, parameter determination method and simulation methods were proved by comparing test and simulated bar strain-time history, dynamic stress-strain curves and failure patterns of specimens. Finally, influences of the aggregate size (4~8mm, 10~14mm and 22~26mm), volume fraction (20%, 30% and 40%) and type (limestone, granite and basalt) on concrete dynamic compressive strength under the strain rate within 30~100s-1 were analyzed. It shows that the dynamic compressive strength of concrete increases first and then decreases with the increase of aggregate size; the dynamic compressive strength of concrete increases with the increase of volume fraction and strength of aggregates.