To investigate the strengthening and toughening effect of fiber on seawater coral aggregate concrete (SCAC) under an impact load, the dynamic mechanical response of SCAC with mono PVA fiber or hybrid PVA-steel fiber at different strain rates was tested by using a 75 mm Split Hopkinson Pressure Bar. The impact properties and failure characteristics were simulated using a software named ANSYS/LS-DYNA. The results indicate that the addition of fibers may improve the embrittlement degree and dynamic mechanical properties of SCAC. The enhancement effect of hybrid fiber on the strain rate sensitivity and dynamic increase factor of SCAC is better than that of mono PVA fiber. The damage degree of SCAC gradually decreases with the increase of PVA fiber content, while the integrity of the hybrid fiber SCAC is better at each strain rate. The number of final deleted elements in the simulated sample is significantly reduced after adding fibers, and the simulated results show the dynamic mechanical properties and failure degree of SCAC with various fiber contents.