Abstract: The defense performance of sandwich structure of steel plate-fiber composite material plate-steel plate structure against fragment was investigated. By the experiment on the fragment simulation projectile (FSP), impacted to different kinds of sandwich plate with high velocity, the ballistic limits of fragment pierced 16 kinds of sandwich plates were obtained, and the influence of structure characteristic on the specific energy absorption of the sandwich plate was analyzed. The results show that the specific energy absorption of laminated sandwich structure on aramid and glass fiber is 8.31% and 16.09% higher than that of a single-layer structure, respectively.The specific energy absorption of the sandwich structure with 8 mm front +8mm core +6 mm back on aramid and glass fiber is 37.72% and 25.35% higher than the one with 4 mm front +8 mm core +10 mm back, respectively. The specific energy absorption of sandwich plate exponentially increases with the thickness of fiber composite sandwich. The tensile properties of middle layer plate is an important factor on the specific energy absorption of the sandwich plate. At the same areal density, the specific energy absorption of the sandwich plate can be significantly improved by adopting thicker faceplate, thinner backboard and laminated structure for middle layer.