Coral aggregate seawater concrete(CASC) with strength grade of C30 and C50 and sisal fiber reinforced coral aggregate seawater concrete(SFCASC) were tested using Hopkinson pressure bar of 75mm diameter. The finite element software LS DYNA was used to simulate the mechanical response of CASC under impact loading. The results show that the dynamic increase factor(DIF) of CASC and SFCASC is related to strain rate (ε·s) and cubic compressive strength (fcu), and the binary function model of DIF with ε·s and fcu is established. According to the failure morphology analysis of the specimens, sisal fiber can effectively enhance the impact resistance of CASC. When the strain rate is 524s-1, the CASC C50specimens are more severely damaged, while the SFCASC C50specimens can maintain complete shape at strain rate of 569s-1, with only a few cracks appearing at the edges. The impact process is simulated by LS DYNA software, and the parameters of HJC model are determined by experimental data. The error between the simulated dynamic compressive strength and the test value is 10%49%, and the error of the dynamic critical strain is 43%183%.