The static and dynamic mechanical properties， intrusion resistance and explosive performance of coral aggregate seawater concrete （CASC） before and after high temperature， and their numerical simulation of a three-dimensional random aggregate mesoscopic model were studied. The results show that the addition of sisal fibers can effectively improve the brittleness of CASC. The residual compressive strength of CASC increases and then decreases as the temperature increases. A two-part equation describing the stress-strain relationship of CASC after high temperature was proposed； the static and dynamic mechanical properties of CASC after high temperature are significantly reduced， and the higher the temperature， the more obvious the high temperature weakening effect. A three-dimensional random aggregate mesoscopic model was established for CASC， and the numerical simulation results are in good agreement with the experimental results.