Abstract: In this paper the relationships between the ballistic energy absorption of aramid fiber, UHMWPE fiber, glass fiber, carbon fiber reinforced composites and areal density, projectile velocity, molding pressure, resin matrix content were investigated and analyzed through lots of ballistic testings. The ballistic resistance of different fiber composites under different conditions was revealed. The study results would be a very valuable reference to the optimal design of ballistic composites and lightweight composite armor.