Unlike the ductile materials, the failure seriously limits the strength of the brittle medium. To understand the mechanism of controlling the dynamic impact strength of diamond-SiC superhard composite under shock wave compression, the numerical simulation is conducted with a lattice-spring model that can describe the mechanical properties of diamond-SiC superhard composite quantitatively. For the simulation, the diamond-SiC superhard composite is constructed by different volume content of diamond and SiC particles. The obtainted shock wave profiles indicate that the dynamic impact strength first increases and then decreases with the increase of diamond content in the sample. The analysis based on the meso-scale damage pattern reveals that such a variation of dynamic impact strength corresponds to three damage evolution modes. When the diamond content increases to a value between 10%–50% in volume percentage, the long slip bands are first dominated, and then becomes short slip bands when the diamond content is 70%, and damage happens mainly in SiC matrix whereas most of the diamond particles are not damaged. When the diamond content is above a critical value of 70% in volume percentage, even the short slip bands are limited heavily, which makes it difficult to relax the shear stress on diamond particles and causes serious damage to diamond particles, finally results in the reduction of dynamic strength.