Coral aggregate seawater concrete(CASC) with strength grade C50 and sisal fiber reinforced coral aggregate seawater concrete (3 kg/m3) were tested using Hopkinson pressure bar with 75mm diameter. The finite element software LS-DYNA was used to model the solid element of the test to simulate the mechanical response of CASC under impact loading. The results show that: (1) CASC and SFCASC have strain rate effects obviously. The relationship between dynamic enhancement factor DIF and strain rate can be fitted by CEB recommended calculation model; (2) When the strain rate is 52.4 s-1, the CASC specimens are more severely damaged, while the SFCASC specimens can maintain a complete shape at a strain rate of 56.9 s-1, with only a few cracks appearing at the edges; (3) The impact process was simulated by LS-DYNA, and 21 parameters of HJC were determine by experimental data. The simulated peak stress value and the experimental value are within 4.9%, and the peak strain value is within18.3 %.